SQL Oracle 11g for Dummy


Chris Zeis Chris Ruel Michael Wessler Learn to: • Set up and manage an Oracle database • Maintain and protect your data • Understand Oracle database architecture • Troubleshoot your database and keep it running smoothly Oracle® 11g Making Everything Easier! ™ Open the book and find: • Two ways to manage your database • What tablespaces are and how to use them • How to automate jobs with the Oracle Scheduler • Ten common installation tips • How to use SQL in Oracle • When to use online, offline, control file, and archive log backups • Database encryption options • Advantages of the Flashback database Chris Zeis is Chief Technology Officer and partner at Perpetual Technologies, Inc., an Oracle partner. Chris Ruel is an Oracle database administrator and consultant. Michael Wessler manages multiple Web applications for the Department of Defense and consults at various government and private agencies. $29.99 US / $32.99 CN / £19.99 UK ISBN 978-0-470-27765-2 Database Management/General Go to dummies.com® for more! Grow wise about Oracle and get going with the leading database software! Are you a seasoned system administrator charged with setting up an Oracle database? Or did you suddenly become a DBA by default? Either way, this book will guide you through the mysteries of Oracle and database administration. Here are the nuts and bolts of creating an Oracle database, implementing it, and keeping it running in tiptop form. • Build it — learn the building blocks behind the database engine and understand Oracle’s physical and logical structures • Prepare for takeoff — review the hardware, software, system, and storage requirements for implementation • Know your environment — recognize and accommodate the differences between Oracle installations on Windows and on Linux/UNIX • Defend it — assess potential threats to your database, configure Oracle Recovery Manager, and create backup and recovery procedures • Maintain it — know the daily and intermittent tasks necessary to keep your database running properly • Head off trouble — implement the system troubleshooting methodology, use Oracle database logs, and explore other diagnostic utilities • Manage it — monitor with Oracle Enterprise Manager Oracle ® 11g Zeis Ruel Wessler Spine: .816 Oracle® 11g FOR DUMmIES‰ by Chris Zeis, Chris Ruel, and Michael Wessler Oracle® 11g FOR DUMmIES‰ Oracle® 11g For Dummies® Published by Wiley Publishing, Inc. 111 River Street Hoboken, NJ 07030-5774 www.wiley.com Copyright © 2009 by Wiley Publishing, Inc., Indianapolis, Indiana Published by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permit- ted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. 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Library of Congress Control Number: 2008942359 ISBN: 978-0-470-27765-2 Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 About the Authors Michael Wessler received his bachelor’s degree in computer technology from Purdue University in West Lafayette, Indiana. He is an Oracle Certified Database Administrator for Oracle 8 and 8i, an Oracle Certified Web Administrator for 9iAS, and a 10g Database Technician. Michael also holds a CISSP security certification. He has administered Oracle databases on NT and various flavors of UNIX and Linux, including clustered Oracle Parallel Server (OPS) environments. He also performs database and SQL/PLSQL tuning for applications. Michael has worked in many IT shops ranging from small dot- com start-ups to large government agencies and corporations. Currently, Michael is a technical manager at Perpetual Technologies Inc., consulting for the U.S. government. In addition to Oracle DBA consulting, Michael has worked extensively as an Oracle 10gAS Web Application Server Administrator. He manages multiple web applications for the Department of Defense and consults at various gov- ernment agencies and in the private sector. Michael also frequently lectures on 10gAS and teaches Oracle Performance Tuning classes. Michael is the author of Oracle DBA on UNIX and Linux and coauthor of Oracle Application Server 10g: J2EE Deployment and Administration, Oracle Unleashed, Second Edition, UNIX Primer Plus, Third Edition, COBOL Unleashed, UNIX Unleashed, Fourth Edition, and High Availablity: SuccessfulImplementation for the Data- Driven Enterprise. Chris Ruel lives in Indianapolis, Indiana. He graduated from Wabash College in 1997 and has been working with Oracle ever since. Currently, he is a con- sultant for Perpetual Technologies, Inc., a technology consulting firm with a focus on database management in the federal and commercial sectors. His clients range from Fortune 500 companies to Department of Defense contracts. He also serves as the vice president of the Indiana Oracle User’s Group and speaks at many local events (Oracle Tech Days) hosted by his company. He served as an Oracle University Instructor from 2000–2004, traveling the country teaching Oracle’s DBA curriculum. Chris is certified in Oracle 8i–10g. He recently received his 10g RAC Certified Expert qualification and is studying for his 11g OCP upgrade exam. When not working on Oracle, Chris enjoys racing and restoring radio control cars. He is also a big fan of Formula 1 auto racing, grilling out with his friends, and watching the Indianapolis Colts play football. Chris Zeis is the Chief Technology Officer and a partner at Perpetual Technologies, Inc. in Indianapolis, Indiana. Chris is the author or coauthor of four books on database technologies. Dedication Michael Wessler: For my Mom, Barb Wessler. A truly unique woman and loving mother; you’re the best! Love always, Mike. Chris Ruel: I dedicate this book to my parents who raised me well. If it wasn’t for them, I don’t know what I would be doing today. Well, my dad always said that I would be digging ditches when he scolded me for not applying myself. Authors’ Acknowledgments Michael Wessler: I would like to thank all my family and friends for being so understanding of the time and commitment it takes when writing a book. It takes countless hours to write one of these and it’s those closest to the authors who lose out during that time. In particular, I’d like to thank Angla Imel for understanding “Sorry, I have to write this weekend.” I’d also like to thank my fellow authors, Chris Zeis and Chris Ruel, for bringing me into this exciting project. Finally, I’d like to thank Tony and Sue Amico not just for get- ting me into technical writing, but for being such wonderful family friends. Chris Ruel: I appreciate the opportunity to be able to cooperate with the other authors of this book, Chris and Mike. A special thanks to the Wiley team (Kyle, Kelly, Tonya, and the mysterious “DB”) for putting up with a newbie author who had a lot of questions and a writing style that had to be wrangled into submission. Lastly, I want thank my lovely girlfriend, Angie, who put up with lots of lost weekends. Also, I apologize to my grilling buddies who wondered where I was half of the summer weekends! Chris Zeis: I would like to personally thank my cowriters, Chris and Mike, for their support. I would also like to acknowledge the people and resources that helped me through this: my business partners Ron and Ryan at Perpetual Technologies, Inc. (PTI), my good friends and leaders at the Defense Finance and Accounting Serivces, The National Guard of Indiana PFO team (CW4 Ferguson and crew), the great folks at Wiley Publishing, and my Limey. 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Corder, Editorial Director Publishing for Consumer Dummies Diane Graves Steele, Vice President and Publisher Composition Services Gerry Fahey, Vice President of Production Services Debbie Stailey, Director of Composition Services Table of Contents Introduction ................................................................. 1 About This Book ..............................................................................................1 Who Are You? ..................................................................................................2 What’s in This Book .......................................................................................2 Part I: You Don’t Have to Go to Delphi to Know Oracle....................2 Part II: Implementing Oracle on Your Own .........................................3 Part III: Caring for an Oracle Database ................................................3 Part IV: Inspecting Advanced Oracle Technologies ..........................3 Part V: The Part of Tens ........................................................................3 Icons in This Book ...........................................................................................4 Where to Go from Here ..................................................................................4 Part I: You Don’t Have to Go to Delphi to Know Oracle ....5 Chapter 1: A Pragmatic Introduction to Oracle. . . . . . . . . . . . . . . . . . . . .7 Introducing a New Kind of Database Management .....................................7 Pooling Resources with Grid Computing .....................................................8 Anticipating Technology and Development Trends ...................................9 Meeting Oracle in the Real World ..................................................................9 Making the Oracle Decision .........................................................................10 Chapter 2: Understanding Oracle Database Architecture . . . . . . . . . .13 Defi ning Databases and Instances ...............................................................13 Deconstructing the Oracle Architecture ....................................................14 Walking Down Oracle Memory Structures .................................................15 Trotting around the System Global Area ....................................................15 Shared pool ...........................................................................................16 Database buffer cache .........................................................................18 Redo log buffer .....................................................................................21 Large pool .............................................................................................22 Java pool ...............................................................................................23 Program Global Area .....................................................................................23 Managing Memory .........................................................................................24 Managing memory automatically .....................................................24 Following the Oracle Processes ...................................................................26 Background processes ........................................................................27 User and server processes .................................................................28 Getting into Physical Structures ..................................................................30 Oracle 11g For Dummies x Getting Physical with Files ...........................................................................30 Data fi les: Where the data meets the disk ........................................31 Control fi les ..........................................................................................32 Redo log fi les ........................................................................................33 Moving to the archives........................................................................35 Server and initialization parameter fi les ...........................................36 Applying Some Logical Structures ..............................................................37 Tablespaces ..........................................................................................38 Segments ...............................................................................................39 Extents ...................................................................................................40 Oracle blocks ........................................................................................41 Chapter 3: Preparing to Implement Oracle in the Real World . . . . . . .43 Understanding Oracle Database Deployment Methodology ...................44 Client-server applications ...................................................................44 Muli-tier applications ..........................................................................45 Component confi gurations .................................................................48 Checking on the Requirements ....................................................................49 User and directory requirements ......................................................50 Hardware requirements .....................................................................53 Software requirements ........................................................................55 Storage requirements .........................................................................56 Other requirements ............................................................................58 Part II: Implementing Oracle on Your Own ................... 61 Chapter 4: Creating an Oracle Database . . . . . . . . . . . . . . . . . . . . . . . . .63 Feeling at Home in Your Environment ........................................................63 Finding the Oracle software owner ...................................................64 Oracle versions ....................................................................................65 Getting to home base .........................................................................65 ORACLE_BASE .....................................................................................66 ORACLE_HOME ...................................................................................66 ORACLE_SID ........................................................................................67 PATH .....................................................................................................67 Sticking with the Oracle Universal Installer and oraenv .........................68 Confi guring an Instance ...............................................................................70 Using PFILE and SPFILES .....................................................................70 Setting parameters in the pfi le and spfi le .........................................71 Creating Your Oracle Database ...................................................................74 Bossing the Database Confi guration Assistant (DBCA) ............................74 Taking database control ....................................................................75 Taking the DBCA steps ........................................................................76 Sharing (a) memory .............................................................................86 Feeling the Post-Confi guration Glow ...........................................................87 xi Table of Contents Chapter 5: Connecting to and Using an Oracle Database. . . . . . . . . . .89 Starting and Stopping the Database ............................................................89 Environmental requirements .............................................................90 Starting the database ..........................................................................92 Stopping the database .........................................................................96 Connecting to the Database Instance ........................................................99 Local versus remote connections ....................................................100 Communication fl ow ..........................................................................100 Setting up tnsnames.ora ...................................................................101 Confi guring the database listener with listener.ora ......................102 Starting and stopping the database listener ..................................104 Testing the connection .....................................................................107 Oracle Net Confi guration Assistant .................................................108 Sidestepping Connection Gotchas ............................................................108 Chapter 6: Speaking the SQL Language . . . . . . . . . . . . . . . . . . . . . . . . .111 Using SQL in Oracle .....................................................................................111 Sharpening the SQL*Plus Tool ..................................................................112 Using SQL Connection Commands ............................................................113 SQL*Plus Profi le Scripts glogin.sql and login.sql ....................................114 SQL*Plus buffer and commands ......................................................115 SQL*Plus commands .........................................................................115 Getting Help from SQL*Plus .......................................................................118 SQL language elements .....................................................................119 Using the Oracle Data Dictionary ....................................................121 Getting a PL/SQL Overview ........................................................................125 Blocking PL/SQL .................................................................................126 Chapter 7: Populating the Database . . . . . . . . . . . . . . . . . . . . . . . . . . . .129 Creating Tablespaces ..................................................................................130 Creating Users and Schemas ......................................................................136 Creating Database Objects .........................................................................140 Object types .......................................................................................140 Object creation methods ..................................................................143 Part III: Caring for an Oracle Database ......................147 Chapter 8: Protecting Your Oracle Database . . . . . . . . . . . . . . . . . . . .149 Assessing Database Threats ......................................................................149 Instance failure ..................................................................................149 Oracle code tree .................................................................................150 Dropped objects ................................................................................150 Media failure .......................................................................................150 Oracle 11g For Dummies xii Corruption ..........................................................................................151 User error............................................................................................152 Getting Your Oracle Recovery Manager ...................................................152 Starting RMAN ....................................................................................152 Confi guring RMAN .............................................................................153 RMAN catalog .....................................................................................156 Putting It in the Archives ............................................................................158 Turning archiving on and off ............................................................159 Archive logs ........................................................................................160 Enabling archiving ............................................................................161 Enabling the Flash Recovery Area ...................................................161 Backup File Types with RMAN ...................................................................164 Backing up with backup sets ............................................................165 Making copies .....................................................................................169 Maintaining the Archives ............................................................................170 Viewing Backup Information ......................................................................171 Recovering Your Oracle Database ............................................................173 Verifying the problem .......................................................................174 Complete recovery ...........................................................................175 Incomplete recovery .........................................................................180 Recovering your database with copies ...........................................182 Chapter 9: Protecting Your Oracle Data. . . . . . . . . . . . . . . . . . . . . . . . .185 Authentication .............................................................................................185 User authentication ...........................................................................186 Password authentication ..................................................................187 Operating system authentication ....................................................190 Granting the Privileged Few .......................................................................191 System privileges ...............................................................................192 Object privileges ................................................................................194 Role Playing ..................................................................................................196 Oracle-supplied roles ........................................................................197 The SYSDBA role ................................................................................198 Virtual Private Database Concept .............................................................198 Auditing Oracle’s Big Brother ...................................................................198 Getting ready to audit .......................................................................199 Enabling and disabling audits ..........................................................202 Auditing system privileges ...............................................................202 Auditing objects .................................................................................204 Verifying an audit ...............................................................................205 Viewing audit information ................................................................207 Turning off audits ..............................................................................207 Encrypting a Database ................................................................................208 xiii Table of Contents Chapter 10: Keeping the Database Running . . . . . . . . . . . . . . . . . . . . .211 Doing Your Chores ......................................................................................211 Making way, checking space ............................................................212 Monitoring space in your segments ................................................216 Growing and shrinking: Tricky tables ............................................217 Checking users ...................................................................................223 Audit records......................................................................................228 System logs .........................................................................................228 Automating Jobs with the Oracle Scheduler ............................................228 Scheduler objects ..............................................................................229 Creating your fi rst scheduler job .....................................................230 Using Oracle Data Pump .............................................................................234 Data Pump Export ..............................................................................235 Data Pump Import ..............................................................................238 Creating Oracle Directories ........................................................................239 Using Data Pump with a Parameter File ...................................................240 Chapter 11: Tuning an Oracle Database. . . . . . . . . . . . . . . . . . . . . . . . .243 Evaluating Tuning Problems ......................................................................243 Tuning Your Database ................................................................................246 Gathering Performance Information with Automatic Workload Repository ................................................................................................247 SQL*Plus method ...............................................................................248 Database Control method .................................................................250 Using the Automatic Database Diagnostic Monitor (ADDM) .................252 Improving Queries with SQL Tuning ........................................................255 Explain plan ........................................................................................256 Active Session History (ASH) ...........................................................258 SQL Access Advisor ...........................................................................259 SQL Tuning Advisor ...........................................................................259 SQL Profi ling and Plan Management ..............................................260 10046 trace event ...............................................................................262 Chapter 12: Troubleshooting an Oracle Database . . . . . . . . . . . . . . . .269 Troubleshooting with System Methodology ............................................270 Identifying the real problem ............................................................270 Performing basic system checks .....................................................272 Performing basic database checks ..................................................278 Analyzing error messages .................................................................281 Developing and applying a solution ...............................................283 Troubleshooting Using Oracle Database Logs ........................................286 Database log infrastructure ..............................................................286 Database alert log ..............................................................................288 Trace and dump fi les .........................................................................290 Listener log .........................................................................................291 Oracle 11g For Dummies xiv Benefi ting from Other Diagnostic Utilities ...............................................292 Oracle Enterprise Manager ...............................................................292 Remote Diagnostic Agent ..................................................................294 Diagnostic database scripts .............................................................296 Chapter 13: Monitoring and Managing with Enterprise Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299 Tasting Oracle Enterprise Manager Flavors .............................................300 OEM Java Console..............................................................................300 OEM Database Control ......................................................................301 OEM Grid Control ..............................................................................301 Confi guring Enterprise Manager with the DBCA .....................................302 Creating and Managing Database Control Users .....................................303 Working with Metrics and Policies ............................................................305 Setting Up Notifi cations ..............................................................................307 Setting Up User Notifi cations .....................................................................308 Navigating Database Control’s Main Page ................................................311 Inspecting the Database Control main page...................................311 Accessing other targets ...................................................................313 Part IV: Inspecting Advanced Oracle Technologies ...... 315 Chapter 14: Flashing Back and Replaying: Advanced Features . . . .317 Rolling Back with Flashback Database .....................................................317 Confi guring and enabling a fl ash back ............................................318 Using restore points ..........................................................................320 Flashing back your database ............................................................321 Using Flashback Data Archive ...................................................................322 Oracle Database Replay ..............................................................................324 Using database replay ......................................................................325 Replaying the workload ...................................................................326 Chapter 15: Using High-Availability Options. . . . . . . . . . . . . . . . . . . . .329 Gathering Real Application Clusters .........................................................330 Exploring RAC Architecture .......................................................................331 Hardware considerations for RAC ...................................................331 Software considerations for RAC .....................................................334 Preparing for a RAC Install .........................................................................336 Tools for managing a RAC installation ............................................337 Oracle RAC application for high availability ..................................341 Defending Oracle Data Guard ....................................................................342 Data Guard architecture ...................................................................342 Physical standby database ...............................................................344 Logical standby database .................................................................347 Performing switchover and failover operations ............................348 xv Table of Contents Part V: The Part of Tens ............................................351 Chapter 16: Top Ten Oracle Installation Do’s . . . . . . . . . . . . . . . . . . . .353 Read the Documentation ............................................................................353 Observe the Optimal Flexible Architecture .............................................354 Confi gure Your Profi le ................................................................................355 Running the Wrong Bit ................................................................................356 Set umask .....................................................................................................356 Become Oracle .............................................................................................357 Stage It ...........................................................................................................357 Patch It .........................................................................................................358 Mind the User and Group IDs .....................................................................359 Back It Up ......................................................................................................360 Chapter 17: Top Ten Database Design Do’s. . . . . . . . . . . . . . . . . . . . . .361 Using Oracle’s Built-In Constraints ...........................................................361 Spreading Out Your IO ................................................................................362 Knowing Data Normalization .....................................................................363 Using Naming Conventions ........................................................................363 Setting Up Roles and Privileges Properly .................................................364 Keeping Ad-Hoc Queries to a Minimum ....................................................364 Enforcing Password Security .....................................................................364 Limiting the Number of DBAs ...................................................................365 Storing Code in the Database .....................................................................365 Testing Your Recovery Strategy ................................................................366 Appendix A: Quick Start Install of Oracle 11g on Linux ....................................................................369 Setting Up the Operating System ...............................................................369 Checking your operating system version .......................................370 Checking your kernel version ..........................................................370 Checking your OS packages .............................................................371 Creating Linux operating system groups and users ......................372 Creating the Oracle Software Owner ........................................................372 Confi guring the Linux Kernel Parameters ................................................373 Creating the ORACLE_BASE directory ............................................374 Confi guring the Oracle user’s environment ...................................374 Installing the Oracle 11g database software ..................................375 Index ....................................................................... 379 Oracle 11g For Dummies xvi Introduction If you are reading this text, chances are you’re considering throwing your- self into the wonderful world of Oracle database administration. The good news is, you have come to right place. The bad news? Well, it’s not really bad news . . . but you have quite an adventure ahead of you. Luckily, the authors of this book, your guides in this adventure, can help smooth out any bumpy roads. With over 35 years of combined Oracle experience, we hope to make understanding the Oracle database a fun, enlightening experience. Oracle is large company with a diverse portfolio of software. It’s constantly growing too. It seems like every other week Oracle releases some slick new product or acquires another company. Don’t let the overwhelming nature of the big picture discourage you. This book imparts a fundamental knowledge of the basics of database administration. An Oracle career is a constant learn- ing process. Establishing a solid understanding of the building blocks behind the database engine will vault you into a successful Oracle career. You might be interested to know that the rock behind all of Oracle’s products is almost always the database. Take comfort in knowing that in the database world, Oracle is the best. Learning the database is the first step to opening an awful lot of doors for you. Starting at this level is key. After reading this book, you will be well on your way to an interesting career filled with challenges and plenty of opportunity. There will always be a need for managing information. Every year we see companies grow and accumulate data at a staggering rate. Databases are not a passing fad like some other areas of information technology. The concept of a relational database has been in circulation for almost 40 years and won’t be going away anytime soon. About This Book Despite this book being titled Oracle 11g For Dummies, we focus on the tenets of Oracle database administration. Not only do we cover many of the features released with the 11g version of the database, but also cover the fundamental building blocks. Many of these concepts and techniques apply to past versions of the Oracle and almost certainly future releases. 2 Oracle 11g For Dummies Sometimes in the book we refer to directories and file locations on both Linux/ UNIX and Windows. Essentially the two can be interchanged with a couple of things in mind. For example, here is an ORACLE_BASE value that you might come across on Linux/UNIX: $ORACLE_BASE: /u01/app/oracle In Windows, /u01 is much like a drive letter. They call it a mount point in Linux/UNIX. Also, variables in Linux/UNIX are frequently prefixed with a dollar sign. Furthermore, the slashes are in opposite directions for each operating system. On Linux/UNIX you call / a forward slash. In Windows, you use a back slash \. Lastly, Windows encapsulates the variable in percent signs. The same previous setting might look like this in Windows: %ORACLE_BASE%: C:\app\oracle We try to give examples of both environments throughout this book. Who Are You? People who find themselves needing or wanting a skill set for Oracle databases come from all backgrounds. You might be an application developer, a system administrator, or even a complete newbie. Many of the folks that we come across in this industry became a database administrator (DBA) by accident. One day, your company finds itself without a DBA, and the next thing you know, that’s you! One trick is to be ready. Above all else, learn on your own and think rather than just react. What’s in This Book Oracle 11g has six different parts with six different major topics. Part I: You Don’t Have to Go to Delphi to Know Oracle Part I helps prepare you for implementation by discussing why you’d choose Oracle in the first place, what’s included in the architecture and 3 Introduction how the elements work together, and what you need to do before starting Oracle database creation. Part II: Implementing Oracle on Your Own Part II gets you into the nitty gritty of Oracle database creation by discuss- ing the tools and actual steps you’ll take. The Database Creation Assistant (DBCA) is detailed here, as well as the SQL language. You can use either tool; automatic or manual setup is your choice. Finally, you read what to populate your Oracle database with. Part III: Caring for an Oracle Database You can’t just create and populate an Oracle database: You have to protect it. Part III has the tools and tips you need to secure both the database and the data within. The less glamorous but no less crucial maintenance chores are detailed in this part, along with basic troubleshooting, should you need to do some. Enterprise Manager makes a star appearance here as well; keep- ing an eye on your database can keep you from having to troubleshoot in the long run. Part IV: Inspecting Advanced Oracle Technologies Part IV reveals some rare Oracle goods, including the flashback database, flashback data archive, and database replay. Rolling back for data recovery is detailed here, and high-availability options Real Application Clusters (RAC) and Data Guard are explained as well. Part V: The Part of Tens Avoid installation mistakes by reading Part V. Ten simple things to avoid (and another 10 to make sure you do) add up to 20 problem solvers. Head off trouble before it starts. 4 Oracle 11g For Dummies Icons in This Book You see these icons throughout this book. They’re a heads-up for different situations. Warnings, if not heeded, will cause you to lose data. And maybe your job. Remembering these bits of information can help you in the long run. And even the short run. Even on a brief walk. Tips can save you time or energy or manpower or resources. We realize all these items are in short supply. Technical Stuff icons indicate things we think are interesting and want to share with you, but can be skipped if you’d rather get straight to the nitty-gritty. Where to Go from Here Jump on in! Keep an open mind and try not to get overwhelmed. Like any skilled profession, it isn’t always easy but you can do it and we think you’ll find it rewarding. This book is written so you can avoid the “too-much- information” reaction. Look at each section as a piece of a big puzzle, and you will soon see how everything starts to take shape. Part I You Don’t Have to Go to Delphi to Know Oracle In this part . . . Need to create a database? Considering Oracle? Already administering an Oracle database? Chapter 1 helps you with the first two by touting Oracle’s advantages. Chapter 2 explains how Oracle database architecture works and Chapter 3 prepares you for actually implementing the Oracle database. Chapter 1 A Pragmatic Introduction to Oracle In This Chapter ▶ Getting familiar with Oracle ▶ Implementing grid computing ▶ Incorporating Oracle into everyday life Oracle 11g is by far the most robust database software on the market today. It’s also the leading database software used and sold all over the world. It has become an enterprise architecture standard for managing data, regardless of the data’s size or complexity. This chapter highlights the reasons to use Oracle 11g. Introducing a New Kind of Database Management Oracle is software that efficiently organizes data in a relational manner. Before Oracle, other database software ran on mainframes and used a hierar- chical data model where data is stored in a tree-like structure as flat files — those crazy COBOL programmers! The relational model is a concept where data is logically stored. These design elements are in the form of tables. Tables have columns, and the columns have attributes (character or number, for example). The tables are organized to store specific data. The tables relate to one another through primary keys. For more clarity, Oracle, the company, was founded on the database soft- ware that transformed the industry into what it is today. Oracle, the com- pany, owns many software products and applications that it has written or acquired, but the database software is still Oracle’s core product. This book focuses more on database administration rather than Oracle appli- cations administration. 8 Part I: You Don’t Have to Go to Delphi to Know Oracle Pooling Resources with Grid Computing Grid computing offers a pool of distributed resources for computing services. It’s simply described as computing as a service, similar to a utility-type model. Oracle supports grid computing with its Real Application Clusters (RAC) capability and its Oracle Enterprise Manager (OEM): ✓ RAC uses Oracle’s clustering software to manage a highly available environment. If you need additional hardware resources (such as memory or CPU), or experience hardware failure, you simply add another node (server) to the grid. (Truthfully, it’s more complicated than that, but you get the point.) ✓ EM manages the databases and hosts, which are also called targets. It has a web interface that gives you a comprehensive view of each target’s state. It handles all the monitoring requirements and provides other web-based tools to interact or perform maintenance with. Together, RAC and EM make up the components to support true grid comput- ing. RAC is a complex architecture that requires a fair amount of systems and database administrator knowledge, which is unfortunately beyond the scope of this book. Chapter 13 covers the capabilities and configuration for EM and its lighter single database version, DB Console. You can find additional information about Oracle RAC at www.oracle.com/database/rac_home.html. Decoding the g in Oracle 11g Oracle has always had some creative market- ing techniques. In the late 1990s, the Internet was booming, and everyone wanted Internet technology. Oracle released an upgraded ver- sion of Oracle 8 and labeled it 8i. i represents the Internet. This addition was a popular move because businesses realized the advantages of providing access via the Internet. Use of the Internet also reduced the labor and cost requirements for client server applications in which the client was installed onto the end user’s PC. As popular as the Internet boom was, grid computing is now the evolution of enterprise architecture management. (Hence the g, which stands for grid.) 9 Chapter 1: A Pragmatic Introduction to Oracle Anticipating Technology and Development Trends Oracle’s success is partially due to anticipating, adapting, and establishing database technology trends. You can choose from numerous designing tools and Integrated Development Environment (IDE) technologies, such as Service Oriented Architecture (SOA), Java, and Extensible Markup Language (XML). These technologies are portable, which reduces hardware or software dependencies and suits standard business-to-business (B2B) processing and communication: ✓ SOA is a style of IT architecture that utilizes a build-once/deploy-many concept. Its root definition includes webcentric services that work together to sustain business processes. SOA separates the application function from the underlying software and hardware to allow better use (or reuse) of application processing. These functions or service units are written to be flexible by design and capable of service-to-service communication. SOA concepts eliminate hard coding and stove piping of applications for better use with other applications. Generally, SOA is engineered for large enterprise architectures that require a scalable, cost-effective approach to application development and maintenance. ✓ Java is a free programming language that standardizes applications across hardware platforms. This write-once/run-anywhere programming language supports object-oriented programming (oop) methodologies. Java is widely used for enterprise-level applications on the web and is very popular because it can run on any operating system without much tweaking. Oracle supported Java shortly after its creation. ✓ XML is an all-purpose language that helps share data across systems via the Internet. It standardizes the programming methods or calls, which allow for B2B communication. XML supports the SOA framework as well. Meeting Oracle in the Real World The Oracle 11g database can support any requirement you have for using and storing data. From financial institutions, such as banks, to human resources or manufacturing applications, Oracle can handle it. Its strengths lie in its vast number of software components and its ability to recover to any point in time. 10 Part I: You Don’t Have to Go to Delphi to Know Oracle General Oracle use supports a variety of applications that are labeled by type. The following list outlines the majority of database types: ✓ Online Transactional Processing (OLTP): Used for transaction-oriented applications where the response is immediate and records are modified or inserted regularly. ✓ Decision Support System (DSS): Used for processing data and making judgments on data for making decisions. A DSS database usually involves many ad hoc queries. ✓ Online Analytical Processing (OLAP): Used for analyzing data. Typically, OLAP is used for business intelligence or data mining, such as budgeting or forecasting. ✓ Hybrid: Acts as a multifunctional database. Most hybrid databases con- tain transactional, processing ad hoc querying, and batch processing. Larger databases that have service-level requirements are generally iso- lated to their own databases for performance and manageability reasons. Uses for Oracle center around data and information. Industries leaders are particularly interested in information. Have you heard the motto “Information Drives Performance”? That motto basically suggests that the performance of a company is relative to the information it has and uses. This information assists in making more competitive and educated decisions. A good example of this process is how Amazon and eBay use their informa- tion. They track user interaction on their Web sites to help define a user’s shopping tendencies and interests. They then make programmatic recom- mendations based on that information to promote purchases, which in turn creates revenue. Information usage in this manner is known as Business Intelligence (BI) and is a common practice among many businesses today. Instead of saying, “Build it and they will come,” Oracle can say, “Get their information and build them something they can’t refuse.” Making the Oracle Decision The decision to use Oracle over other technologies or database software can be a difficult one. Several things can influence your decision: ✓ Cost ✓ Available expertise ✓ Project scope ✓ Scale 11 Chapter 1: A Pragmatic Introduction to Oracle Most of our clients decided to use Oracle based on available expertise because pricing is fairly competitive across database companies. In one case, Microsoft SQL Server was almost chosen because the developers had ASP/ VB.NET experience. If the developers were Java eccentric, the database soft- ware would have never been discussed. Management, however, realized that it could use the pre-existing Oracle database infrastructure and still develop with Microsoft products. Microsoft Access and even Microsoft Excel have their place, but if you want functionality, scalability, recoverability, and security, Oracle is the best choice. Linux gurus also use MySQL or PostgreSQL. Both are free for public use. The difficulty in using or managing MySQL or PostgreSQL is finding quali- fied expertise. You also need to consider the software support capability of the product. Oracle support provides a deep, mature group and a knowledge base for issues, such as bugs or general guidance. In comparison to other database software products, Oracle has a similar level of complexity in installing, configuring, and maintaining it. Senior expert-level professionals are sometimes necessary for particular issues, but most novices to Oracle can achieve success without much training or guid- ance. We’ve trained many DBAs in our day, and they all had very little knowl- edge of Oracle but were eager to get their hands dirty. A good understanding of information technology and computers in general definitely helps with the learning curve. Oracle runs on all the common and latest operating system versions of Linux, UNIX, Microsoft Windows, Mainframes, and Mac. It provides the same func- tionality and utilities regardless of the operating system or hardware. It also supports 64-bit architecture to add additional memory space for large applica- tions. You can purchase licensing per CPU or per named user. Additionally, Oracle provides lower-cost licensing for its standard editions. Oracle licensing information is available at www.oracle.com/corporate/ pricing/technology-price-list.pdf. 12 Part I: You Don’t Have to Go to Delphi to Know Oracle Chapter 2 Understanding Oracle Database Architecture In This Chapter ▶ Structuring memory ▶ Checking the physical structures ▶ Applying the irreducible logic of the logical structures Understanding the Oracle architecture is paramount to managing a database. If you have a sound knowledge of the way Oracle works, it can help all sorts of things: ✓ Troubleshooting ✓ Recovery ✓ Tuning ✓ Sizing ✓ Scaling As they say, that list can go on and on. That’s why a solid knowledge of the inner workings of Oracle is so important. In this chapter we break down each process, file, and logical structure. Despite the dozens of different modules in the database, you should come away with a good understanding of what they are, why they’re there, and how they work together. This chapter is more conceptual than it is hands-on, but it gives you a solid base for moving forward as you begin working with Oracle. 14 Part I: You Don’t Have to Go to Delphi to Know Oracle Defining Databases and Instances In Oracle speak, an instance is the combination of memory and processes that are part of a running installation. The database is the physical component or the files. You might hear people use the term database instance to refer to the entire running database. However, it’s important to understand the distinction between the two. Here are some rules to consider: ✓ An instance can exist without a database. Yes, it’s true. You can start an Oracle instance and not have it access any database files. Why would you do this? • This is how you create a database. There’s no chicken-or-egg debate here. You first must start an Oracle instance; you create the database from within the instance. • An Oracle feature called Automatic Storage Management uses an instance but isn’t associated with a database. ✓ A database can exist without an instance, but would be useless. It’s just a bunch of magnetic blips on the hard drive. ✓ An instance can only access one database. When you start your instance, the next step is to mount that instance to a database. An instance can only mount one database at a time. ✓ You can set up multiple instances to access the same set of files or one database. Clustering is the basis for Oracle’s Real Application Clusters feature. Many instances on several servers accessing one central data- base allows for scalability and high availability. Deconstructing the Oracle Architecture You can break the Oracle architecture into the following three main parts: ✓ Memory: The memory components of Oracle (or any software, for that matter) are what inhabit the RAM on the computer. These structures only exist when the software is running. For example, they instantiate when you start an instance. Some of the structures are required for a running database; others are optional. You can also modify some to change the behavior of the database, while others are static. 15 Chapter 2: Understanding Oracle Database Architecture ✓ Processes: Again, Oracle processes only exist when the instance is running. The running instance has some core mandatory processes, whereas others are optional, depending on what features are enabled. These processes typically show up on the OS process listing. ✓ Files and structures: Files associated with the database exist all the time — as long as a database is created. If you just install Oracle, no database files exist. The files show up as soon as you create a database. As with memory and process, some files are required whereas others are optional. Files contain your actual database objects: the things you create as well as the objects required to run the database. The logical structures are such things as tables, indexes, and programs. Maybe you could say that the Oracle architecture has two-and-a-half parts. Because files contain the structures, we lump those two together. The following sections get into more detail about each of these main components. Walking Down Oracle Memory Structures Oracle has many different memory structures for the various parts of the software’s operation. Knowing these things can greatly improve how well your database runs: ✓ What each structure does ✓ How to manage it In most cases, more memory can improve your database’s performance. However, sometimes it’s best to use the memory you have to maximize performance. For example, are you one of those “power users” who likes to have ten pro- grams open at once, constantly switching between applications on your desk- top? You probably know what we’re talking about. The more programs you run, the more memory your computer requires. In fact, you may have found that upgrading your machine to more memory seems to make everything run better. On the other hand, if you are really a computer nerd, you might go into the OS and stop processes that you aren’t using to make better use of the memory you have. Oracle works in much the same way. 16 Part I: You Don’t Have to Go to Delphi to Know Oracle Trotting around the System Global Area The System Global Area (SGA) is a group of shared memory structures. It con- tains things like data and SQL. It is shared between both Oracle background processes and server processes. The SGA is made up of several parts called the SGA components: ✓ Shared pool ✓ Database buffer cache ✓ Redo log buffer ✓ Large pool ✓ Java pool The memory areas are changed with initialization parameters. ✓ You can modify each parameter individually for optimum tuning (only for the experts). ✓ You can tell Oracle how much memory you want the SGA to use (for everyone else). Say you want Oracle to use 1GB of memory. The database actually takes that 1GB, analyzes how everything is running, and tunes each component for optimal sizing. It even tells you when it craves more. Shared pool Certain objects and devices in the database are used frequently. Therefore, it makes sense to have them ready each time you want to do an operation. Furthermore, data in the shared pool is never written to disk. The shared pool itself is made up four main areas: ✓ Library cache ✓ Dictionary cache ✓ Quickest result cache ✓ SQL result cache A cache is a temporary area in memory created for a quick fetch of information that might otherwise take longer to retrieve. For example, the cache’s mentioned in the preceding list contain pre-computed information. Instead of a user having to compute values every time, the user can access the information in a cache. 17 Chapter 2: Understanding Oracle Database Architecture The library cache The library cache is just like what it’s called: a library. More specifically, it is a library of ready-to-go SQL statements. Each time you execute a SQL statement, a lot happens in the background. This background activity is called parsing. Parsing can be quite expensive. During parsing, some of these things happen: ✓ The statement syntax is checked to make sure you typed everything correctly. ✓ The objects you’re referring to are checked. For example, if you’re trying access a table called emp, Oracle makes sure it exists in the database. ✓ Oracle makes sure that you have permission to do what you’re trying to do. ✓ The code is converted into a database-ready format. The format is called byte-code or p-code. ✓ Oracle determines the optimum path or plan. This is by far the most expensive part. Every time you execute a statement, the information is stored in the library cache. That way, the next time you execute the statement not much has to occur (such as checking permissions). The dictionary cache The dictionary cache is also frequently used for parsing when you execute SQL. You can think of it as a collection of information about you and the data- base’s objects. It can check background-type information. The dictionary cache is also governed by the rules of the Least Recently Used (LRU) algorithm: If it’s not the right size, information can be evicted. Not having enough room for the dictionary cache can impact disk usage. Because the definitions of objects and permission-based information are stored in database files, Oracle has to read disks to reload that information into the dictionary cache. This is more time-consuming than getting it from the memory cache. Imagine a system with thousands of users constantly executing SQL . . . an improperly sized dictionary cache can really hamper performance. Like the library cache, you can’t control the size of the dictionary cache directly. As the overall shared pool changes in size, so does the dictionary cache. The quickest result cache The result cache is a new Oracle 11g feature and it has two parts: 18 Part I: You Don’t Have to Go to Delphi to Know Oracle ✓ SQL result cache: This cache lets Oracle see that the requested data — requested by a recently executed SQL statement — might be stored in memory. This lets Oracle skip the execution part of the, er, execution, for lack of a better term, and go directly to the result set, if it exists. What if your data changes? We didn’t say this is the end-all-performance- woes feature. The SQL result cache works best on relatively static data (like the description of an item on an e-commerce site). Should you worry about the result cache returning incorrect data? Not at all. Oracle automatically invalidates data stored in the result cache if any of the underlying components are modified. ✓ PL/SQL function result cache: The PL/SQL function result cache stores the results of a computation. For example, say you have a function that calculates the value of the dollar based on the exchange rate of the Euro. You might not want to store that actual value since it changes constantly. Instead, you have a function that calls on a daily or hourly rate to determine the value of the dollar. In a financial application this could happen thousands of times an hour. Therefore, instead of the function executing, it goes directly to the PL/SQL result cache to get the data between the rate updates. If the rate does change, then Oracle re- executes the function and updates the result cache. Least Recently Used algorithm If the library cache is short on space, objects are thrown out. Statements that are used the most stay in the library cache the longest. The more often they’re used, the less chance they have of being evicted if the library cache is short on space. The library cache eviction process is based on what is called the Least Recently Used (LRU) algorithm. If your desk is cluttered, what do you put away first? The stuff you use the least. You can’t change the size of the library cache yourself. The shared pool’s overall size determines that. If you think too many statements are being evicted, you can boost the overall shared pool size if you’re tuning it yourself. If you’re letting Oracle do the tuning, it grabs free memory from elsewhere. Database buffer cache The database buffer cache is typically the largest portion of the SGA. It has data that comes from the files on disk. Because accessing data from disk is slower than from memory, the database buffer cache’s sole purpose is to cache the data in memory for quicker access. 19 Chapter 2: Understanding Oracle Database Architecture The database buffer cache can contain data from all types of objects: ✓ Tables ✓ Indexes ✓ Materialized views ✓ System data In the phrase database buffer cache the term buffer refers to database blocks. A database block is the minimum amount of storage that Oracle reads or writes. All storage segments that contain data are made up of blocks. When you request data from disk, at minimum Oracle reads one block. Even if you request only one row, many rows in the same table are likely to be retrieved. The same goes if you request one column in one row. Oracle reads the entire block, which most likely has many rows, and all columns for that row. It’s feasible to think that if your departments table has only ten rows, the entire thing can be read into memory even if you’re requesting the name of only one department. Buffer cache state The buffer cache controls what blocks get to stay depending on available space and the block state (similar to how the shared pool decides what SQL gets to stay). The buffer cache uses its own version of the LRU algorithm. Heap area There aren’t a lot of interesting things to say about the heap area within the context of this book. Basically, the heap area is a bunch of smaller memory components in the shared pool. Oracle determines their sizes and tunes them accordingly. Only the nerdiest of Oracle DBAs will search the dark nether-regions of the Internet for heap area information. It’s not readily available from Oracle in the documentation, and the informa- tion you do find may or may not be accurate. If all I have done was make you more curi- ous, look at the dynamic performance view in the database called V$SGASTAT to get a list of all the other heap area memory component names. 20 Part I: You Don’t Have to Go to Delphi to Know Oracle A block in the buffer cache can be in one of three states: ✓ Free: Not currently being used for anything ✓ Pinned: Currently being accessed ✓ Dirty: Block has been modified, but not yet written to disk Free blocks Ideally, free blocks are available whenever you need them. However, that probably isn’t the case unless your database is so small that the whole thing can fit in memory. The LRU algorithm works a little differently in the buffer cache than it does in the shared pool. It scores each block and then times how long it has been since it was accessed. For example, a block gets a point each time it’s touched. The higher the points, the less likely the block will be flushed from memory. However, it must be accessed frequently or the score decreases. A block has to work hard to stay in memory if the competition for memory resources is high. Giving each block a score and time prevents this type of situation from aris- ing: A block is accessed heavily at the end of the month for reports. Its score is higher than any other block in the system. That block is never accessed again. It sits there wasting memory until the database is restarted or another block finally scores enough points to beat it out. The time component ages it out very quickly once you no longer access it. Dirty blocks A modified block is a dirty block. To make sure your changes are kept across database shutdowns, these dirty blocks must be written from the buffer cache to disk. The database names dirty blocks in a dirty list or write queue. You might think that every time a block is modified, it should be written to disk to minimize lost data. This isn’t the case — not even when there’s a commit (when you save your changes permanently)! Several structures help prevent lost data. Furthermore, Oracle has a gambling problem. System performance would crawl if you wrote blocks to disk for every modification. To combat this, Oracle plays the odds that the database is unlikely to fail and only writes blocks to disk in larger groups. Don’t worry; it’s not even a risk against lost data. Oracle is getting performance out of the database right now at the pos- sible expense of a recovery taking longer later. Because failures on properly managed systems rarely occur, it’s a cheap way to gain some performance. However, it’s not as if Oracle leaves dirty blocks all over without cleaning up after itself. 21 Chapter 2: Understanding Oracle Database Architecture Block write triggers What triggers a block write and therefore a dirty block? ✓ The database is issued a shutdown command. ✓ A full or partial checkpoint occurs — that’s when the system periodically dumps all the dirty buffers to disk. ✓ A recovery time threshold, set by you, is met; the total number of dirty blocks causes an unacceptable recovery time. ✓ A free block is needed and none are found after a given amount of searching. ✓ Certain data definition language (DDL) commands. (DDL commands are SQL statements that define objects in a database. You find out more about DDL in Chapter 6.) ✓ Every three seconds. ✓ Other reasons. The algorithm is complex and we can’t be certain with all the changes that occur with each software release. The fact is the database stays pretty busy writing blocks in an environment where there are a lot changes. Redo log buffer The redo log buffer is another memory component that protects you from yourself, bad luck, and Mother Nature. This buffer records every SQL state- ment that changes data. The statement itself and any information required to reconstruct it is called a redo entry. Redo entries hang out here temporarily before being recorded on disk. This buffer protects against the loss of dirty blocks. Dirty blocks aren’t written to disk constantly. Imagine that you have a buffer cache of 1,000 blocks and 100 of them are dirty. Then imagine a power supply goes belly up in your server and the whole system comes crashing down without any dirty buffers being written. That data is all lost, right? Not so fast. . . . The redo log buffer is flushed when these things occur: ✓ Every time there’s a commit to data in the database ✓ Every three seconds ✓ When the redo buffer is 1⁄3 full ✓ Just before each dirty block is written to disk 22 Part I: You Don’t Have to Go to Delphi to Know Oracle Why does Oracle bother maintaining this whole redo buffer thingy when instead, it could just write the dirty buffers to disk for every commit? It seems redundant. ✓ The file that records this information is sequential. Oracle always writes to the end of the file. It doesn’t have to look up where to put the data. It just records the redo entry. A block exists somewhere in a file. Oracle has to find out where, go to that spot, and record it. Redo buffer writes are very quick in terms of I/O. ✓ One small SQL statement could modify thousands or more database blocks. It’s much quicker to record that statement than wait for the I/O of thousands of blocks. The redo entry takes a split second to write, which reduces the window of opportunity for failure. It also only returns your commit if the write is successful. You know right away that your changes are safe. In the event of failure, the redo entry might have to be re-executed during recovery, but at least it isn’t lost. Large pool We’re not referring to the size of your neighbor’s swimming pool. Not everyone uses the optional large pool component. The large pool relieves the shared pool of sometimes-transient memory requirements. These features use the large pool: ✓ Oracle Recovery Manager ✓ Oracle Shared Server ✓ Parallel processing ✓ I/O-related server processes Because many of these activities aren’t constant and only allocate memory when they’re running, it’s more efficient to let them execute in their own space. Without a large pool configured, these processes steal memory from the shared pool’s SQL area. That can result in poor SQL processing and constant resizing of the SQL area of the shared pool. Note: The large pool has no LRU. Once it fills up (if you size it too small) the processes revert to their old behav- ior of stealing memory from the shared pool. 23 Chapter 2: Understanding Oracle Database Architecture Java pool The Java pool isn’t a swimming pool filled with coffee (Okay, we’re cutting off the pool references.) The Java pool is an optional memory component. Starting in Oracle 8i, the database ships with its own Java Virtual Machine (JVM), which can execute Java code out of the SGA. In our experience, this configuration is relatively rare. In fact, we see this where Oracle-specific tools are installed. However, don’t let that discourage you from developing your own Java-based Oracle applications. The fact is, even though Oracle has its own Java con- tainer, many other worthwhile competing alternatives are out there. Program Global Area The Program Global Area (PGA) contains information used for private or session-related information that individual users need. Again, this used to be allocated out of the shared pool. In Oracle 9i, a memory structure called the instance PGA held all private information as needed. This alleviated the need for the shared pool to constantly resize its SQL area to meet the needs of individual sessions. Because the amount of users constantly varies, as do their private memory needs, the instance PGA was designed for this type of memory usage. The PGA contains the following: ✓ Session memory • Login information • Information such as settings specific to a session (for example, what format to use when dates are displayed) ✓ Private SQL area • Variables that might be assigned values during SQL execution • Work areas for processing specific SQL needs: sorting, hash-joins, bitmap operations • Cursors 24 Part I: You Don’t Have to Go to Delphi to Know Oracle Managing Memory You have basically three ways to manage the memory in your instance: ✓ Automatically by letting Oracle do all the work ✓ Manually by tuning individual parameters for the different memory areas ✓ Combination of automatic and manual by using your knowledge of how things operate, employing Oracle’s advice infrastructure, and letting Oracle take over some areas First, a quick note on Oracle automation. Through the last three releases of Oracle (9i, 10g, and 11g) the database has become more automated in areas that were previously manual and even tedious at times. This isn’t to say that soon it will take no special skill to manage an Oracle database. Exactly the opposite: When more mundane operations are automated, it frees you up as the DBA to focus on the more advanced features. We’ve had great success implementing automated features for clients. It frees up our resources to focus on things such as high availability and security, areas that require near full-time attention. Thank goodness we don’t have to spend hours watching what SQL is aging out of the shared pool prematurely. We recommend that you manage memory automatically in Oracle 11g. For that reason, we only cover automatic management in this chapter. Managing memory automatically When you create your database, you can set one new parameter that takes nearly all memory tuning out of your hands: MEMORY_TARGET. By setting this parameter, all the memory areas discussed earlier in this chapter are automatically sized and managed. After you type this parameter in SQL*Plus — show parameter memory_target — (the SQL command-line interface available in Oracle), you see this output on the screen: NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ memory_target big integer 756M Automatic memory management lets you take hold of the amount of memory on the system and then decide how much you want to use for the database. It’s never obvious what value you should choose as a starting point. Answer these questions to help set the value: 25 Chapter 2: Understanding Oracle Database Architecture ✓ How much memory is available? ✓ How many databases will ultimately be on the machine? ✓ How many users will be on the machine? (If many, we allocate 4MB per user for process overhead.) ✓ What other applications are running on the machine? Before the users get on the machine, consider taking no more than 40 percent of the memory for Oracle databases. Use this formula: (GB of memory × .40) / Number of Eventual Databases = GB for MEMORY_TARGET per database For example, if your machine had 8GB of memory and will ultimately house two databases similar in nature and only 100 users each, we would have this equation: (8 × .40) / 2 = 1.6GB for MEMORY_TARGET per database. To help determine whether you have enough memory, Oracle gives you some pointers if you know where to look. It’s called the Memory Target Advisor. Find it from the command line in the form of the view V$MEMORY_TARGET_ ADVICE. As seen in Figure 2-1, find it in the Database Control home page by clicking Advisor Central➪Memory Advisors➪Advice. Figure 2-1: MEMORY_ TARGET offers advice. 26 Part I: You Don’t Have to Go to Delphi to Know Oracle Whatever you choose for the MEMORY_TARGET setting isn’t all the memory Oracle uses. That’s why you should have an idea of how many sessions there will be before you make the final determination. For instance, this parameter only covers memory used by the SGA and PGA. Every single session that connects to the database requires memory asso- ciated with its OS or server process. This adds up. One of our clients has nearly 3,000 simultaneous connections eating up about 16GB of memory outside the SGA and PGA. The client’s machine has 64GB of memory and the MEMORY_TARGET is set at 16GB. Following the Oracle Processes When you start and initiate connections to the Oracle instance, many pro- cesses are involved, including ✓ The component of the Oracle instance that uses the Oracle programs ✓ Code to gain access to your data There are no processes when the Oracle instance is shut down. Some of the processes are mandatory and others are optional depending on the features you’ve enabled. It can also depend on your OS. Three types of processes are part of the instance: ✓ Background processes are involved in running the Oracle software itself. ✓ Server processes negotiate the actions of the users. ✓ User processes commonly work outside the database server itself to run the application that accesses the database. Background processes In Oracle 11g, you can have around 212 background processes. We say around because it varies by operating system. If this sounds like a lot, don’t be scared. Many are multiples of the same process (for parallelism and taking advantage of systems with multiple CPUs). Table 2-1 shows the most common background processes. By default, no processes have more than one instance of their type started. More advanced tuning features involve parallelism. To see a complete list of all the background processes on your OS, query V$BGPROCESS. 27 Chapter 2: Understanding Oracle Database Architecture Table 2-1 Common Background Processes Background Process Name Description PMON The process monitor (or P-MOM, because it cleans up after you like your mother did when you were a kid) manages the system’s server processes. It cleans up failed processes by releasing resources and rolling back uncommitted data. SMON The system monitor is primarily responsible for instance recovery. If the database crashes and redo information must be read and applied, the SMON takes care of it. It also cleans and releases temporary space. DBWn The database writer’s sole job is taking dirty blocks from the dirty list and writing them to disk. There can be up to 20 of them, hence the n. It starts as DBW0 and continues with DBW1, DBW2, and so on. After DBW9, it continues with DBWa through DBWj. An average system won’t see more than a few of these. LGWR The log writer process flushes the redo log buffer. It writes the redo entries to disk and signals a completion. CKPT The checkpoint process is responsible for initiating check points. A check point is when the system periodically dumps all the dirty buffers to disk. Most commonly, this occurs when the database receives a shutdown command. It also updates the data file headers and the control files with the check point information so the SMON know where to start recovery in the event of a system crash. ARCn Up to 30 archiver processes (0–9, a–t) are responsible for copying filled redo logs to the archived redo storage area. If your database isn’t running in archive mode, this process shuts down. CJQ0 The job queue coordinator checks for scheduled tasks within the database. These jobs can be set up by the user or can be internal jobs for maintenance. When it finds a job that must be run it spawns the following goodie. J000 A job queue process slave actually runs the job. There can be up to 1,000 of them (000–999). DIA0 The diagnosability process resolves deadlock situations and investigates hanging issues. VKTM The virtual keeper of time sounds like a fantasy game character but simply provides a time reference within the database. 28 Part I: You Don’t Have to Go to Delphi to Know Oracle Other background processes exist, as you can tell by the “around 212” number we stated at the beginning of this section. However, those described in Table 2-1 are the most common, and you will find them on almost all Oracle installations. When you engage some of Oracle’s more advanced func- tionality, you’ll see other processes. It’s very easy to see these background processes if you have an Oracle instal- lation available on Linux or UNIX. In Figure 2-2, ps –ef |grep ora_lists the background processes. This works very well since all background processes begin with ora_. Figure 2-2: The Oracle background process list. User and server processes Because user and server processes are intertwined, we discuss the two together. However, they are distinct and separate processes. As a matter of fact, they typically run on separate machines. A very simple example: When you start SQL*Plus on a Windows client, you get a user process called sqlplus. exe. When a connection is made to the database on a Linux machine, you get a connection to a process named something like oracle or ora_S000_. The server process serves. It does anything the user requests of it. It is responsible for reading blocks into the buffer cache. It changes the blocks if requested. It can create objects. 29 Chapter 2: Understanding Oracle Database Architecture Server processes can be one of two types: ✓ Dedicated ✓ Shared The type depends on how your application operates and how much memory you have. You’re first presented with the choice of dedicated or shared when you create your database with Oracle’s Database Creation Assistant (DBCA). However, you can change it one way or the other later on. Dedicated server architecture Each user process gets its own server process. This is the most common Oracle configuration. It allows a server process to wait on you. If the resources can support dedicated connections, this also is the most responsive method. However, it can also use the most memory. Even if you’re not doing anything, that server process is waiting for you. Not that it’s a bad thing. Imagine, though, 5,000 users on the system sitting idle most of the time. If your applications can’t use connection pools (similar to shared server processes), your database probably won’t survive and perform adequately for more than a day. Shared server architecture Just as the name implies, the server processes are shared. Now, instead of a server process waiting on you hand and foot, you only have one when you need it. Think of a server process as a timeshare for Oracle. It’s more cost-effective (in terms of memory), and you almost always have one available when you need it (provided the infrastructure is properly configured). On a system with 5,000 mostly idle users, you might be able to support them with only 50 server processes. You must do these things for this to work properly: ✓ Make sure the number of concurrent database requests never exceeds the number of shared servers configured. ✓ Make sure users don’t hold on to the processes for long periods. This works best in a fast transaction-based environment like an e-commerce site. ✓ Have a few extra CPU cycles available. All the interprocess communica- tion seems to have small CPU cost associated with it over dedicated server processes. 30 Part I: You Don’t Have to Go to Delphi to Know Oracle The fact is shared server configurations are less common in today’s environ- ment where memory is cheap. Most applications these days get around the problems associated with too many dedicated servers by using advanced con- nection pooling on the application server level. You should know about some other limitations: DBA connections must have a dedicated server. Therefore, a shared server environment is actually a hybrid. Shared servers can coexist with a dedicated server. Getting into Physical Structures The physical structures are the files that actually live on disk in the system. We call them physical because they have measurable physical properties (even though they’re just magnetic blips on a rotating platter). However, they are present even if you completely power down the system. The physical structures are accessed by way of the memory and processes of the running Oracle instance. In essence, the memory and processes are translators that convert the magnetic blips into something you can read and understand. Well . . . most of the time you can understand it. Many different types of files are required (and optional) to run an Oracle database: ✓ Data files ✓ Control files ✓ Redo log files ✓ Archive log files ✓ Server and initialization parameter files Knowing what each of these files does greatly increases your database man- agement success. Getting Physical with Files Many types of files are created with your database. Some of these files are for storing raw data. Some are used for recovery. Some are used for housekeep- ing or maintenance of the database itself. In the next few sections, we take a look at the various file types and what they are responsible for storing. 31 Chapter 2: Understanding Oracle Database Architecture Data files: Where the data meets the disk Data files are the largest file types in an Oracle database. They store all the actual data you put into your database, as well as the data Oracle requires to manage the database. Data files are a physical structure: They exist whether the database is open or closed. Data files are also binary in nature. You can’t read them yourself without starting an instance and executing queries. The data is stored in an organized format broken up into Oracle blocks. Whenever a server process reads from a data file, it does so by reading at the very least one complete block. It puts that block into the buffer cache so that data can be accessed, modified, and so on. It’s also worth noting that the data file is physically created using OS blocks. OS blocks are different from Oracle blocks. OS blocks are physical, and their size is determined when you initially format the hard drive. You should know the size of your OS block. Make sure that it’s equal to, or evenly divisible into, your Oracle block. Most of the time Oracle data files have an extension of .DBF (short for data- base file?). But the fact of the matter is that file extensions in Oracle don’t matter. You could name it .XYZ and it will function just fine. We feel it is best practice to stick with .DBF because that extension is used in 95 percent of databases. In every data file, the very first block stores the block header. To be specific, depending on your Oracle block size, the data file header block may be several blocks. By default, the header block is 64k. Therefore, if your Oracle block size is 4k, then 16 header blocks are at the beginning of the file. These header blocks are for managing the data file’s internal workings. They contain ✓ Backup and recovery information ✓ Free space information ✓ File status details Lastly, a tempfile is a special type of database file. Physically, it’s just like a regular data file, but it only holds temporary information. For example, a tempfile is used if you perform sorts on disk or if you’re using temporary tables. The space is then freed to the file either immediately after your opera- tion is done or once you log out of the system. 32 Part I: You Don’t Have to Go to Delphi to Know Oracle Figure 2-3 shows that by executing a simple query against V$TEMPFILE and V$DATAFILE you can see a listing of the data files in your database. Figure 2-3: Data files listed. Control files The control file is a very important file in the database — so important that you have several copies of it. These copies are placed so that losing a disk on your system doesn’t result in losing all of your control files. Typically, control files are named with the extension .CTL or .CON. Any extension will work, but if you want to follow best practice, those two are the most popular. Control files contain the following things: ✓ Names and locations of your data files and redo log files ✓ Recovery information ✓ Backup information ✓ Checkpoint information ✓ Archiving information ✓ Database name ✓ Log history ✓ Current logging information Control files contain a host of other internal information as well. Typically, control files are some of the smaller files in the database. It’s difficult to tell you how big they are because it varies depending on this: 33 Chapter 2: Understanding Oracle Database Architecture ✓ How many files your database has ✓ How much backup information you’re storing in them ✓ What OS you’re using As mentioned earlier, it’s important that you have several copies of your con- trol files. If you were to lose all of your control files in an unfortunate failure, it is a real pain to fix. Redo log files Redo log files store the information from the log buffer. They’re written to by the Log Writer (LGWR). Again, you can’t read these binary files without the help of the database software. Typically, redo log files are named with the extension .LOG or .RDO. It can be anything you want, but best practice indicates one of those two extensions. Also, redo log files are organized into groups and members. Every database must have at least two redo log groups. Redo log files contain all the information necessary to recover lost data in your database. Every SQL statement that you issue changing data can be reconstructed by the information saved in these files. Redo log files don’t record select statements. If you forget what you selected, you’re just going to have to remember that on your own! The optimal size for your redo log files depends on how many changes you make to your database. The size is chosen by you when you set up the data- base and can be adjusted later. When the LGWR is writing to a redo log file, it does so sequentially. It starts at the beginning of the file and once it is filled up, it moves on to the next one. This is where the concept of groups comes in. Oracle fills each group and moves to the next. Once it has filled all the groups, it goes back to the first. You could say they are written to in a circular fashion. If you have three groups, it would go something like 1,2,3,1,2,3, . . . and so on. Each time a group fills and the writing switches, it’s called a log switch opera- tion. These things happen during a log switch operation: ✓ The LGWR finishes writing to the current group. ✓ The LGWR starts writing to the next group. ✓ A database check point occurs. ✓ The DBWR writes dirty blocks out of the buffer cascade. 34 Part I: You Don’t Have to Go to Delphi to Know Oracle How fast each group fills up is how you determine its size. By looking at all the things that occur when a log switch happens, you might agree that it is a fairly involved operation. For this reason, you don’t want frequent log switches. The general rule is that you don’t want to switch log files more often than every 15–30 minutes. If you find that happening, consider increasing the size of each group. Because these redo log files may be involved in recovery operations, don’t lose them. Similar to control files, redo log files should be configured with mirrored copies of one another. And, as with control files, each member should be on a separate disk device. That way, if a disk fails and the database goes down, you still have recovery information available. You should not lose any data. Each copy within a group is called a member. A common configuration might be three groups with two members apiece, for a total of six redo log files. The group members are written to simultaneously by the log writer. ✓ How many groups are appropriate? The most common configuration we come across is three. You want enough that the first group in the list can be copied off and saved before the LGWR comes back around to use it. If it hasn’t been copied off, the LGWR has to wait until that operation is complete. This can severely impact your system. Thankfully, we rarely see this happen. ✓ How many members are appropriate? It depends on how paranoid you are. Two members on two disks seems to be pretty common. However, it isn’t uncommon to see three members on three disks. More than that and you’re just plain crazy. Well, not really. It’s just that the more mem- bers you have, the more work the LGWR has to do. It can impact system performance at the same time offering very little return. We commonly get this question: If my disks are mirrored at the hardware level, do I need more than one member on each group? After all, if a disk fails, I have another one right there to pick up the slack. Unfortunately, you get different answers depending on who you ask. Ask us, and we’ll recommend at least two members for each group: ✓ Oracle still recommends two members for each group as a best practice. ✓ Depending on how your hardware is set up, you may have the same disk controller writing to your disk mirrors. What if that controller writes corrupt gibberish? Now both your copies are corrupted. Separating your members across two different disks with different controllers is the safest bet. 35 Chapter 2: Understanding Oracle Database Architecture Moving to the archives Archive log files are simply copies of redo log files. They’re no different from redo log files except that they get a new name when they’re created. Most archive log files have the extension .ARC, .ARCH, or .LOG. We try to use .ARC as that seems most common. Not all databases have archive log files. It depends on whether you turn on archiving. By turning on archiving, you can recover from nearly any type of failure providing two things: ✓ You have a full backup. ✓ You haven’t lost all copies of the redo or archive logs. There is a small amount of overhead with database archiving: ✓ I/O cost: The ARCn process has to copy each redo log group as it fills up. ✓ CPU cost: It takes extra processing to copy the redo logs via the ARCn process. ✓ Storage cost: You have to keep all the archive logs created between each backup. Relatively speaking, each of these costs is small in terms of the return you get: recovering your database without so much as losing the dot over an i. We typically recommend that, across the board, all production databases archive their redo logs. Sometimes, archiving isn’t needed, such as in a test database used for testing code. You can easily just copy your production database to revive a broken test. We’re not recommending not archiving on test databases. Sometimes the test database is important enough to archive. We’re just saying that sometimes you can get by without incurring the extra overhead. You should keep archive log files for recovery between each backup. Say you’re doing a backup every Sunday. Now say that your database loses files due to a disk failure on Wednesday. The recovery process would be restor- ing the lost files from the last backup, and then telling Oracle to apply the archive log files from Sunday all the way up to the failure on Wednesday. It’s called rolling forward, and we talk about it in Chapter 8. Like control files and redo log files, it’s best practice to have more than one copy of each of your archive log files. They should go to two different destina- tions on different devices, just like the others. You can’t skip over a lost archive log. 36 Part I: You Don’t Have to Go to Delphi to Know Oracle Server and initialization parameter files Server and initialization parameter files are the smallest files on your system: ✓ PFILE, or parameter file, is a text version that you can read and edit with a normal text editor ✓ SPFILE, or server parameter file, is a binary copy that you create for the database to use after you make changes. Typically, these files with an .ORA extension. Personally, we have never seen anything but that. It’s best practice for you to continue the tradition. PFILEs and SPFILEs have information about how your running database is configured. This is where you configure the following settings: ✓ Memory size ✓ Database and instance name ✓ Archiving parameters ✓ Processes ✓ Over 1,900 other parameters Wait, what was that? Over 1900 parameters to configure and tweak? Don’t be frightened. The fact is 99 percent of your database configuration is done with about 30 of the main parameters. The other 1,900 are for uncommon con- figurations that require more expert adjustment. As a matter of fact, of those 1,900, over 1,600 are hidden. Sorry if we scared you a little there. We just want you to have the whole picture. Whenever you start your database, the very first file read is the parameter file. It sets up all your memory and process settings and tells the instance where the control files are located. It also has information about your archiving status. The PFILEs and SPFILEs are under the directory where you installed the data- base software. This directory is called the ORACLE_HOME: ✓ Linux/UNIX: $ORACLE_HOME/dbs ✓ Windows: %ORACLE_HOME\database It should have a specific naming structure. For example, if your database name is dev11g, the files would be named as follows: ✓ The PFILE would be called initdev11g.ora. ✓ The SPFILE would be called spfiledev11g.ora. 37 Chapter 2: Understanding Oracle Database Architecture By naming them this way and putting them in the appropriate directory, Oracle automatically finds them when you start the database. Else, you have to tell Oracle where they are every time you start the database; that just isn’t convenient. We recommend you keep the PFILE and SPFILE in the default locations with the default naming convention for ease of administration. Applying Some Logical Structures After you know the physical structures, you can break them into more logical structures. All the logical structures that we talk about are in the data files. Logical structures allow you to organize your data into manageable and, well, logical, pieces. Without logical breakdown of the raw, physical storage, your database would ✓ Be difficult to manage ✓ Be poorly tuned ✓ Make it hard to find data ✓ Require the highly trained and special skill set of a madman Figure 2-4 show the relationship of logical to physical objects. The arrow points in the direction of a one-to-many relationship. Figure 2-4: Relationship between logical and physical structures in the database. Segments Extents Oracle blocks Tablespaces OS blocks Data files Logical Structures Physical Structures 38 Part I: You Don’t Have to Go to Delphi to Know Oracle Tablespaces Tablespaces are the first level of logical organization of your physical storage. Every 11g database should have the following tablespaces: ✓ SYSTEM: Stores the core database objects that are used for running the database itself. ✓ SYSAUX: For objects that are auxiliary and not specifically tied to the core features of the database. ✓ UNDO: Stores the rollback or undo segments used for transaction recovery. ✓ TEMP: For temporary storage. Each tablespace is responsible for organizing one or more data files. Typically, each tablespace might start attached to one data file, but as the database grows and your files become large, you may decide to add storage in the form of multiple data files. The next step to getting your database up and running? Creating some areas to store your data. Say your database is going to have sales, human resources, accounting data, and historical data. You might have the following tablespaces: ✓ SALES_DATA ✓ SALES_INDEX ✓ HR_DATA ✓ HR_INDEX ✓ ACCOUNTING_DATA ✓ ACCOUNTING_INDEX ✓ HISTORY_DATA ✓ HISTORY_INDEX Separating tables and indexes both logically and physically is common in a database. ✓ Since tablespaces must have at least one data file associated with them, you can create them so data files are physically on separate devices and therefore improve performance. ✓ You can harden our databases against complete failure. Tablespaces can be backed up and recovered from one another independently. Say you lose a data file in the SALES index tablespace. You can take only the SALES_INDEX tablespace offline to recover it while human resources, accounting, and anyone accessing historical data is none the wiser. 39 Chapter 2: Understanding Oracle Database Architecture We discuss actual tablespace creation in Chapter 7. Keep in mind that when deciding on the logical organization, it pays to sit down and map out all the different activities your database will support. If possible, create tablespaces for every major application and its associated indexes. If your database has especially large subsets of data, sometimes it pays to separate that data from your regular data as well. For example, say you’re storing lots of still pictures. Those pictures probably never change. If you have a tablespace dedicated to them, you can make it read only. The tablespace is taken out of the checkpointing process. You can also back it up once, and then do it again only after it changes. That reduces the storage required for backups, plus it speeds up your backup process. Segments Segments are the next logical storage structure next to tablespaces. Segments are objects in the database that require physical storage and include the following: ✓ Tables ✓ Indexes ✓ Materialized views ✓ Partitions These object examples are not segments and don’t store actual data: ✓ Views ✓ Procedures ✓ Synonyms ✓ Sequences The latter list of objects don’t live in a tablespace with segments. They’re pieces of code that live in the SYSTEM tablespace. Whenever you create a segment, specify what tablespace you want it to be part of. This helps with performance. For example, you probably want the table EMPLOYEES stored in the HR_DATA tablespace. In addition, if you have an index on the LAST_NAME column of the EMPLOYEES table, you want to make sure it is created in the HR_INDEXES tablespace. That way, when people are searching for and retrieving employee information, they’re not trying to read the index off the same data file that the table data is stored in. 40 Part I: You Don’t Have to Go to Delphi to Know Oracle Extents Extents are like the growth rings of a tree. Whenever a segment grows, it gains a new extent. When you first create a table to store items, it gets its first extent. As you insert data into that table, that extent fills up. When the extent fills up, it grabs another extent from the tablespace. When you first create a tablespace, it’s all free space. When you start creating objects, that free space gets assigned to segments in the form of extents. Your average tablespace is made up of used extents and free space. When all the free space is filled, that data file is out of space. That’s when your DBA skills come in and you decide how to make more free space avail- able for the segments to continue extending. Extents aren’t necessarily contiguous. For example, when you create or items table and insert the first 1,000 items, it may grow and extend several times. Now your segment might be made up of five extents. However, you also create a new table. As each table is created in a new tablespace, it starts at the beginning of the data file. After you create your second table, your first table may need to extend again. Its next extent comes after the second extent. In the end, all objects that share a tablespace will have their extents intermingled. This isn’t a bad thing. In years past, before Oracle had better algorithms for storage, DBAs spent a lot of their time and efforts trying to coalesce these extents. It was called fragmentation. It’s a thing of the past but we still see people getting all up in arms about it. Don’t get sucked in! Just let it be. Oracle 11g is fully capable of managing such situations. I also want to mention situations where you have multiple data files in a tablespace. If a tablespace has more than one data file, the tablespace auto- matically creates extents in a round-robin fashion across all the data files. This is another Oracle performance feature. Say you have one large table that supports most of your application. It lives in a tablespace made of four data files. As the table extends, Oracle allocates the extents across each data file like this: 1,2,3,4,1,2,3,4,1,2,3,4 . . . and so on This way, Oracle can take advantage of the data spread across many physical devices when users access data. It reduces contention on segments that have a lot of activity. 41 Chapter 2: Understanding Oracle Database Architecture Oracle blocks We have mentioned these at least twice before. They had to be mentioned when talking about the buffer cache and data files. Let’s fill in a little more information. An Oracle block is the minimum unit that Oracle will read or write at any given time. Oracle usually reads and writes more than one block at once, but that’s up to Oracle these days. You used to have more direct control but now of the option is automatically tuned. You can tune it manually to a certain extent, but most installations are best left to Oracle. Regardless, blocks are the final logical unit of storage. Data from your tables and indexes are stored in blocks. The following things happen when you insert a new row into a table: ✓ Oracle finds the segment. ✓ Oracle asks that segment if there’s any room. ✓ The segment returns a block that’s not full. ✓ The row or index entry is added to that block. If no blocks are free for inserts, the segment grabs another free extent from the tablespace. By the way, all this is done by the server process to which you’re attached. Oracle blocks themselves also have a physical counterpart as the data files do. They are made up of OS blocks. It is the formatted size of the minimum unit of storage on the device. Oracle blocks should be evenly divisible by your OS block size. Oracle blocks should never be smaller than your OS block size. We discuss Oracle block sizing more in Chapter 4. 42 Part I: You Don’t Have to Go to Delphi to Know Oracle Chapter 3 Preparing to Implement Oracle in the Real World In This Chapter ▶ Understanding Oracle Deployment Methodologies ▶ Verifying system requirements ▶ Planning server and disk configuration ▶ Post-installation setup steps Before you create databases and store your data, you need to plan a few things that will make your implementation much easier. First and fore- most, you need to determine your overall database architecture. Databases don’t exist as standalone entities; they’re part of an information system, and you need to understand how that system is laid out. This chapter looks at two of the most common deployment methodologies and helps you deter- mine which method is right for you. After you determine the right overall deployment plan, you need to make sure that your target environment meets the necessary requirements to host Oracle. This chapter not only looks at obvious requirements, such as server hardware and software, but it also looks at less reviewed (yet critical) requirements, such as user, configuration, and storage considerations. This chapter gives you the knowledge to make good judgments of where and how your Oracle database will be implemented. 44 Part I: You Don’t Have to Go to Delphi to Know Oracle Understanding Oracle Database Deployment Methodology Oracle databases don’t simply exist in isolation; they act as part of a com- puter system. Before installing your database, you need to know how your database fits into the overall system architecture. Some systems are more complex than others, but most fall into the following basic categories: ✓ Client-server ✓ Multi-tier ✓ Component configurations Knowing which category your database fits into will make a big difference during your system setup because you’ll know the specific needs of your database. Client-server applications Client-server applications (sometimes called two-tier) are those in which the user’s workstation has the application program installed and, during execution, the program accesses data stored on a remote database server. Although you have some wiggle room here, the workstation handles the pre- sentation and application logic, and the database server acts as a data store. Figure 3-1 shows how a client-server configuration works. Figure 3-1: A client- server application. Client Workstation Oracle Net / JDBC / ODBC Port 1521 Client Application - Presentation - Application Logic - tnsnames.ora Database Server Oracle Database - Data Access - Data Manipulation 45 Chapter 3: Preparing to Implement Oracle in the Real World In Figure 3-1, the workstation (client-tier) handles the application logic and presentation to the user. Application logic may be implanted via many dif- ferent languages, but common examples include PowerBuilder, MS Visual Basic, Java applications, and even some versions of Oracle Forms and Reports. When these client-side applications need data, they access the database via ODBC (Open Database Connectivity), JDBC (Java Database Connectivity), or Oracle Net using client-side tnsnames.ora files. These database communication protocols allow connectivity from any client to any database, including Oracle. On the database tier, the database stores the data and, via users, roles, and permissions, it provides that data to the application in response to SQL que- ries and data manipulation language (DML) statements (which are simply SQL statements that manipulate, or change, the data). Depending on whether you’re using a fat or thin client, some of the application logic and processing may be off-loaded to the database tier. Processing on the database server often makes sense because a database server can do much more intensive processing and number-crunching than even the largest workstation. Data processing is commonly executed via database procedures, functions, and packages, which process the data into a smaller result set to be returned to the client for presentation to the user. Many people have claimed that client-server is dead. If it is, why are so many client-server applications still out there? Sure, the client-server architecture is older, and many newer applications exist in the multi-tier world. However, a simple client-server application still meets the immediate needs of a busi- ness in some situations. Or the client-server application may be an exist- ing legacy application that does its job — so the business has no need to upgrade. Regardless, while we don’t recommend developing new, large-scale systems on this model, we can’t deny that client-server applications still exist in many organizations. Muli-tier applications Multi-tier applications are the current industry standard and compose mul- tiple web, application, and database servers providing content to thin clients with presentation via a web browser. Ever wonder what’s behind the scenes when you login to a web application for online purchases or banking? Well, it looks something like Figure 3-2. 46 Part I: You Don’t Have to Go to Delphi to Know Oracle Figure 3-2: Multi-tier architecture. Client Workstation HTTP AJP Oracle Net Firewall HTTPS Web Browser - Presentation Web Server - HTTP/S Listener Application Server - Application Logic Client Workstation Web Browser - Presentation Database Server Oracle Database - Data Access - Data Manipulation In Figure 3-2, the client-tier is merely a web browser accessing a web server. Displaying content to the user is the primary purpose of the client in this architecture; no actual processing occurs at this layer within the browser. Presentation occurs most commonly via HTML (HyperText Markup Language), but it can also be within a Java Applet or ActiveX component and use JavaScript for more dynamic formatting and content. Communication from the browser to the web server occurs via HTTP (HyperText Transfer Protocol) or HTTPS for secure (encrypted) data. Web servers conceptually act as web listeners; they receive requests from brows- ers and return formatted result sets with little processing on their own. Once on the web server, the browser request is parsed and sent to the appropriate application server for processing. The application server component may be on the same physical server as the web server, or it may be on another physi- cal server. By far, the most common web server is Apache, or one of its com- mercial derivates, with 50 percent of the marketshare according to http:// news.netcraft.com/archives/web_server_survey.html. At the application server level, the user request is processed using the rele- vant application logic. One very common method is to use a Java application server, such as Tomcat, Orion, or Glassfish. In this case, the program logic is executed inside a Java Virtual Machine (JVM), which acts as the runtime environment for the program code. Another popular tool is Oracle 10gAS (Application Server). Within 10gAS, the program may run as Oracle Forms, Reports, Discoverer, or even Java via Oracle Containers for J2EE (OC4J). Regardless of the product, it’s within the application server component that the application logic is executed. 47 Chapter 3: Preparing to Implement Oracle in the Real World During processing on the application server, it’s common to need database access to query, create, update, or delete data. The application server com- municates with the database server via protocols, such as JDBC or Oracle Net, to access the data. During this time, the application server is accessing the database on behalf of the user making the application request. Rather than connecting as a named, distinct user such as JSMITH, the application server connects using a generic web account (such as WEB_USER). Multiple simul- taneous connections from the application server to the database form a con- nection pool that allows any database connection to access data for a request. Connection pooling is a performance benefit because only a few database con- nections can service thousands of requests on behalf of many users. Once logged into the database instance, the generic web user queries or executes DML on behalf of the application server, which is processing an actual user request. The connection pooled web user doesn’t have schema ownership into the database; it has only those permissions needed to access or update data on behalf of the application server. During this time, normal database roles, permissions, and grants are utilized. Additionally, database program logic implemented in PL/SQL via procedures, functions, and pack- ages is often executed. After the data result set is generated on the database-tier, it’s passed back to the application server for more processing. Next, the results are relayed back through the web server and across the network for presentation to the user via their web browser. Sounds complicated with all the various components? You may think so at first, but good reasons exist for breaking the system into web, application, and database components: ✓ You can use components from different vendors in a “best of breed” configuration. For example, you can use a free Apache web server instance coupled with Tomcat or Glassfish for a cheap application server component. Then tie that to the power of the Oracle database, and you have yourself a solid system at lower costs! ✓ As more users come online, you can add more web, application, or database server instances to boost your processing power. Rather than buying bigger servers, just buy smaller servers. ✓ After you have a series of multiple servers, you gain fault tolerance. If a web server crashes or the application server needs maintenance, no problem — the redundant servers will pick up the workload. Hopefully, these benefits show why muti-tier system architectures are the industry standard and have surpassed client-server systems. 48 Part I: You Don’t Have to Go to Delphi to Know Oracle Component configurations In client-server and multi-tier systems, the Oracle database was the core of the system because it holds the data. Existing as the primary data store for the entire system is the most common use of an Oracle database, but it’s not the only time you’ll have to install Oracle. Often, these databases serve a support role by acting as secondary data stores for larger Commercial Off The Shelf (COTS) applications. In these cases, Oracle databases act as repositories storing specialized data for use within a larger system. During installation of the larger system, the Oracle database is installed as a sup- porting component. One common example of an Oracle repository you may be familiar with is Oracle Designer. You can use this Oracle developer tool to design, create, and store application code (among other things), and it resides on the user’s desktop. When the user starts Oracle Designer, it prompts for an Oracle repository to connect to, and the user specifies that information. It is within that repository that all the objects to be used by the Designer desktop are stored. In this case, Designer is following the client-server model described in the section “Client-server applications,” earlier in this chapter. Oracle Internet Directory (OID) is a more current example of Oracle acting as a subcomponent within a multi-tiered environment. OID is Oracle’s implemen- tation of an LDAP (Lightweight Directory Access Protocol). LDAPs are hierarchi- cally defined (not relational) data-stores (not databases) that allow systems quick lookup access of data. A common example is an email address book, which doesn’t contain a lot of updates or deeply layered data — it’s just a need for quick lookups of a piece of data, which is the core use of an LDAP. Another common LDAP use is to store users and their credentials so that web application servers can simply look up a person to see whether she is authorized to access a system. After all, you don’t want to allow just anyone into your system! This credential verification is a big need for Oracle’s Application Server products (10gAS), and an LDAP is the solution. And, of course, with Oracle being a database company first and foremost, it opted to put its LDAP implementation inside an Oracle database, which is OID (see Figure 3-3). 49 Chapter 3: Preparing to Implement Oracle in the Real World Figure 3-3: A component architecture with Oracle Internet Directory. Client Workstation HTTP AJP Oracle Net LDAP Firewall HTTPS Web Browser - Presentation Web Server - HTTP/S Listener Application Server - Application Logic Client Workstation Web Browser - Presentation Database Server Oracle Database - Data Access - Data Manipulation LDAP Directory Server Oracle Database Directory (OID) - Oracle Internet Authentication - User Figure 3-3 shows how a specialized Oracle database can provide authentica- tion via OID/LDAP for a larger system that also happens to use Oracle for the backend database where traditional customer data is stored. The OID is just a necessary component in a larger system. The idea of this section isn’t to make you an authority on Oracle Designer or OID. Rather, it’s to show you that Oracle is more than just “the database” for large applications; Oracle also appears in critical support roles. Your Oracle installation may be for one of these support components, but don’t discount the importance of such a database. Without the supporting Oracle compo- nent database the overall system would not be functional. Checking on the Requirements Oracle databases are very good at storing and accessing data, but a little prep work will allow them to run even better. Before installing the Oracle software, you need to do a little homework to ensure that your server will support the software. (For installation information, see Part VI.) 50 Part I: You Don’t Have to Go to Delphi to Know Oracle Each release of Oracle databases is better than the previous one, but each version also has minor updates to the installation requirements. Oracle does a good job of documenting these detail updates for the myriad versions it supports and making them available on its web site at oracle.com/technol- ogy/documentation/database.html. Pay particular interest to the Installation Guide and Quick Installation Guide for your operating system (OS). You can avoid many of the installation problems people experience by just spending a few minutes reviewing the Oracle Installation Guide for your spe- cific OS and meeting those requirements. A quick review of this guide before installing a new version can save you hours troubleshooting issues because you’re not making mistakes that Oracle has already documented. User and directory requirements On UNIX- and Linux-based systems, you install and run Oracle as a specific user and group. In most cases, the user is called oracle, the primary group oinstall, and the secondary group dba. Here’s a sample of how this user is defined: $ id uid=501(oracle) gid=501(oinstall) groups=501(oinstall),502(dba)) On Windows systems, the software should be installed by a member of the Local Administrators group for the machine. It’s common to have multiple versions of Oracle running on the same machine simultaneously. To avoid chaos, you need to organize how and where each version is installed. The framework commonly used to organize and install Oracle software is called Optimal Flexible Architecture (OFA). You can use this organizational hierarchy to install your Oracle software based on software versions and common directories used by all versions. Key to the OFA are the directory environment variables ORACLE_BASE and ORACLE_HOME: ✓ ORACLE_BASE is where you can find common software used by all Oracle software versions; it’s the base of underlying Oracle code trees. ✓ ORACLE_HOME is a subdirectory and denotes the location where a spe- cific version of Oracle database software is installed, often associated with one or more database instances. Here’s the hierarchy: //app/oracle/product// 51 Chapter 3: Preparing to Implement Oracle in the Real World Table 3-1 describes each level of the hierarchy. Table 3-1 OFA Hierarchy Level Description Base directory, file system, or drive name app Directory name denoting application software will be located in this tree oracle Owner of the software and is defined as ORACLE_ BASE product Holding directory for software trees version number Directory with unique version number containing the actual software installation. Defined as ORACLE_ HOME Here’s how this hierarchy exists on UNIX or Linux: /u01/app/oracle/product/11.1.0 And on Windows: d:\app\oracle\product\11.1.0 In both cases, the oracle is ORACLE_BASE, and 11.1.0 is ORACLE_HOME. The Oracle installation tool guides you through identifying these locations, but you need to understand why each location is defined so you can better orga- nize your software installations. In the ORACLE_BASE directory, an Oracle Inventory directory is created as oraInventory. Within this directory, Oracle logs a record of all Oracle software that has been installed, patched, and removed from the server. This informa- tion is used so that the Oracle Universal Installer (OUI) and the OPatch can track software dependencies during installation and patching operations. The Oracle Inventory is managed automatically by the OUI and OPatch utilities. Underneath ORACLE_BASE is an admin directory with named subdirectories for each Oracle database, as well as backup, config tool logs, the flash recov- ery area, and product directories: $ ls $ORACLE_BASE admin backup cfgtoollogs diag flash_recovery_area product Of particular importance, under each ORACLE_BASE/admin/ subdirectory are directories for auditing, data pump, configuration, and wallet files: 52 Part I: You Don’t Have to Go to Delphi to Know Oracle $ ls $ORACLE_BASE/admin/* /u01/app/oracle/admin/db01: adump dpdump pfile wallet /u01/app/oracle/admin/dev11g: adump dpdump pfile wallet Table 3-2 shows you directories for auditing, Data Pump, configuration, and Oracle wallets. Table 3-2 Database admin Directories Directory Purpose adump Audit file location. Can generate many files, but are generally not very large dpdump Location for Data Pump utility pfile Location for database startup configuration files wallet Oracle Wallets storage area In previous versions of Oracle, bdump, cdump, and udump directories appeared underneath each database admin directory storing alert, trace, and core dump files. However, starting in Oracle 11g, these directories appear in trace, alert, and incident subdirectories under the diag/rdbms/ directory. In Table 3-3, you see the location of key trace and alert files. Table 3-3 Trace and Alert File Locations Directory Purpose alert Location of the ever important activity log file for your database. cdump Location of core dump files. trace Location of database or user-generated trace files reflecting an error event. Replaces bdump and udump directories. incident Location of additional trace files. Oracle manages software installations based on their ORACLE_HOME. Multiple ORACLE_HOMEs can exist on a server, each corresponding to a different version of the database. Different versions can generally coexist without conflict as they only share the Oracle Inventory, oratab file, and database listener process. This separation of the software into different directories allows this separation and management to occur. Here’s an example of multiple ORACLE HOMEs: 53 Chapter 3: Preparing to Implement Oracle in the Real World $ ls 11.1.0 10.2.0 9.2.0 In the preceding example, you see multiple ORACLE_HOMEs installed into different directories. Defining your environment variable settings to point to a specific ORACLE HOME determines which one you’re using. Database files (data, index, control, redo) are preferably stored in separate file systems allocated specifically for this purpose and separated by database names: /u02/oradata/dev11g /u03/oradata/dev11g /u04/oradata/dev11g The oracle user in group dba needs to be able to read, write, and execute to the ORACLE_BASE and ORACLE_HOME directories, subdirectories, and files, as well as the database files themselves. If other users on this server need to execute programs on the server side, such as SQL*Plus or export/import or SQL*Loader, they will need execute permissions on corresponding executa- bles and, in some cases, libraries. Hardware requirements Oracle software requires a minimum amount of memory, virtual memory, CPU speed, and disk space to install successfully. If you lack these require- ments, at best, the software will run slowly; at worst, it may not even install at all. Don’t forget to consider what other software is executing on the machine, too, both now and in the foreseeable future. It does little good to meet the data- base requirements and then add more software that will consume hardware resources beyond what the server can support. Several vital server requirements to check include the following: ✓ Memory: The working area for programs as they execute, memory is key to fast performance. The kind you care about here is Random Access Memory (RAM), and it’s measured in megabytes (MB) or, more com- monly, gigabytes (GB). Oracle database SGAs are memory pools. Having large amounts of memory available allows you to have larger SGAs. The more memory you have available, the more options you have when man- aging the ever important SGA. 54 Part I: You Don’t Have to Go to Delphi to Know Oracle ✓ Virtual memory: When a program or data is being executed, it’s stored in memory. When that same program isn’t actively being executed but will be momentarily, it’s stored in virtual memory (for MS Windows) or swap (for UNIX/Linux operating systems). This system administrator- defined disk area operates as a slower extension of memory. Generally, virtual memory is sized to between .75 to twice the size of installed memory. ✓ CPU speed: The clock speed of your CPU (central processing unit) is important. If the CPU is old (and slow) and is laboring just to keep the OS running, then adding an Oracle database isn’t a good idea. Additionally, if so many other programs are running and consuming the CPU, you can have problems trying to run Oracle. For as much hype as you hear about CPU speeds, a better solution than having one fast CPU is having multiple CPUs; even if they are a little slower, more CPUs are better than fewer. ✓ Disk: The disk is where the Oracle database software is stored — essen- tially on your hard drive. The disk is only where your Oracle software itself is installed; it’s not where your actual database files will exist with all your data. Oracle software installations take only a few gigabytes, but actual databases can take terabytes. Like most software, a minimum value is listed by the vendor but more is generally better. Table 3-4 lists the minimum hardware requirements for 11g databases. Table 3-4 Minimum Hardware Requirements Operating System RAM Virtual Memory/Swap CPU Disk Windows 1GB 2 times RAM 550 MHz 5GB Linux 1GB .75 to 2 times RAM 550 MHz 3.5GB When identifying where you’re going to install the software, make sure that you allow space for growth — don’t just go with the minimum hardware requirements. After you install the software, you’ll have patches to apply (which take space), and log files will grow as the software runs; you don’t want to run out of space! 55 Chapter 3: Preparing to Implement Oracle in the Real World Software requirements Your OS version must meet the Oracle requirements. Being close isn’t good enough. Oracle 11 is currently supported to operate on the following requirements in these specific Windows and Linux operating environments: ✓ Windows 2000 with Service Pack 1 or later (32 bit only) ✓ Windows 2003 and 2003 R2 ✓ Windows XP Professional ✓ Windows Vista with Business, Enterprise, and Ultimate editions ✓ Asianux 2.0 and 3.0 ✓ Oracle Enterprise LINUX 4.0 and 5.0 ✓ Red Hat Enterprise LINUX 4.0 and 5.0 ✓ SUSE LINUX Enterprise Server 10.0 Oracle is also supported on multiple UNIX operating environments such as Sun Solaris, HP HP-UX, and IBM AIX. Furthermore, an OS has software bug fixes applied to it in the form of patches, which create a patch level. Patches aren’t a negative reflection of any particular operating system; they’re simply part of the software develop- ment life cycle. Oracle requires a specific minimum patch level per OS for the database software to even install. It’s common to have the system administrator apply software patches before the Oracle installer will execute. Hopefully, your system administrator rou- tinely applies patches as they become available so that your OS is relatively current. Keep in mind that often a server needs to be restarted for the OS patches to take effect. The ramification is that if you need a patch applied, you may have to schedule time for a server to be restarted, which, depending on your organization’s policies, may take several days or weeks. How do you know what patches need to be applied? One way is to check the Oracle Installation and Configuration Guide as it lists the minimum requirements. Sometimes, though, the requirements change faster than the documentation, and you need to check the Release Notes for detailed updates. These notes appear on the Oracle web site under Installing and Upgrading for your specific OS version (oracle.com/pls/db111/homepage) or on the software installation media. 56 Part I: You Don’t Have to Go to Delphi to Know Oracle An easier method is to let the Oracle Universal Installer (executed via the runInstaller program) do the checking for you. With the –executeSysPrereqs option flag, the OUI program runs checks on the OS for version, patching, and hardware requirements prior to installing any software. It makes sure that at least the minimum requirements are met before software is installed, thus reducing problems during installation. The OUI is also a great way to generate a list of necessary patches so that you can have your system administrator install them. To run the OUI, execute it as $ runInstaller -executeSysPrereqs Starting Oracle Universal Installer... Checking swap space: must be greater than 500 MB. Actual 3813 MB Passed Checking monitor: must be configured to display at least 256 colors Storage requirements Your ORACLE_HOME directory will host your software files and binaries. Once installed, the ORACLE_HOME doesn’t grow excessively except for patches. The ORACLE_BASE will grow some during logging operations and even more if trace and core dump files are generated. However, it’s the actual database files that can take lots of space and grow rapidly. Database files (data, index, redo, temp) should be stored separately from the installation files and binaries for management, growth, and performance reasons. Many smaller databases are installed on whatever disk space is available on the server (called internal drives). Cramming multiple, smaller databases onto internal drives is often not optimal for several reasons: ✓ You have negative performance impacts when database files are on non- dedicated disks. ✓ Internal disks are often not as fast or flexible as external disk solutions. ✓ You need to consider special backup and recovery issues because these files have different backup requirements than other files (see Chapter 8). Despite these issues, many people still cram their databases onto internal disks until their databases grow too large. One downside of having a large or medium-sized database is that it takes a lot of disk space. Often the database will be larger than the internal disk that comes with your server, so you need another option, such as storing your database on a large disk farm or disk storage array attached to your database server. 57 Chapter 3: Preparing to Implement Oracle in the Real World Storage arrays can be complex devices, but they offer many benefits. Using attached storage allows your database to grow because the storage admin- istrator can allocate more space as needed. The reading and writing of data is often buffered in memory on the array to increase performance. Advanced configurations of disk mirroring and stripping are also available. Disk optimization basics Planning and configuring storage for a large database is an art and science, but a few basic concepts should be understood by everyone. First, not all data files are accessed equally. Some types of files are read/written to far more often than others. Classify your files into either high- or low-utilization categories and then iso- late the high-utilization files onto separate disks. The idea is not to have all your high-utilization files on the same physical disk; spreading them out over multiple disks balances the read/write operations to reduce contention and improve performance. Not all disks are the same speed, so make sure that your high-utilization files are on the fastest disks you have. A second key item deals with disk redun- dancy and RAID levels. Redundancy Array of Inexpensive/Independent Disks is a categoriza- tion of how your data is spread across multiple disks. Striping is data written across multiple disks to speed up read/write access because there is less contention on an individual disk. Mirroring is maintaining multiple redundant copies of data on multiple disks so that if one disk fails, the data is still available (providing fault tolerance). Parity is a mathematical tech- nique of maintaining special bits of data to re- create data if a disk is lost. The following table shows the most common RAID levels in use today. RAID Level Description Benefit 0 Striping with no mirroring or parity Performance benefit only 1 Mirroring with no striping Improved fault tolerance 0+1 Striping and mirroring Improved fault tolerance and performance 5 Striping with parity over multiple disks Performance and fault tolerance without doubling needed disk space Other RAID levels exist, but most times people use RAID 0+1 or RAID 5. You can achieve the best performance and fault tolerance with RAID 0+1, but it comes at the price of doubling your storage requirements because you’re writing your data twice (mirroring). RAID 5 provides improved performance and fault tolerance while using less disk space, but the benefits aren’t as pronounced due to the overhead of maintaining parity bits. 58 Part I: You Don’t Have to Go to Delphi to Know Oracle In addition to internal drives or attached storage, Oracle provides you three choices when determining what kind of disk to store your Oracle database files on: ✓ Raw devices: These unformatted (uncooked) disk partitions don’t have an existing file system structure. While they’re necessary for some advanced Oracle configurations and offer a performance improvement, they’re difficult to manage and administer. Many people feel those nega- tives outweigh the benefits. ✓ Automatic Storage Management (ASM): A step up from raw devices, with ASM, Oracle manages the disk for you. It uses partitioned disks, but Oracle sets up the disk groups and spreads the data across them to improve performance by balancing disk Input/Output (I/O) operations. The idea is to offload the work of managing the disks from the system administrator and place it in control of Oracle. ✓ File system: The opposite of raw devices, these formatted disk parti- tions (cooked) have traditional mount points and directories like most people would expect. This disk is by far the most common type of disk configuration because it’s easy to use, intuitive, and the standard for most servers. While raw and ASM-based systems offer benefits, tradi- tional file systems are still the de facto standard. Planning the storage for your database is one of the most critical factors for your database. If you get it right, performance will be fast, and management of the database growth will be simple. Mess it up or don’t pay attention to it, and you’ll have slow performance, and management will be difficult. You can almost always add more memory or CPUs if you need them, but if a large data- base is stored incorrectly, fixing it can be a large undertaking. Other requirements Oracle databases don’t operate in isolation merely for the edification on the DBA; they operate to support a computer system, which in turn meets a busi- ness need. Identifying the details of the computer system the database must support will likely identify some unique requirements. The following sections describe common examples of additional require- ments and questions to ask before installation. Oracle version What version of Oracle is needed for this system? It’s common to use the newest version of the database available, but is the application software certified for that version? Often times, a Commercial Off The Shelf (COTS) 59 Chapter 3: Preparing to Implement Oracle in the Real World software package may not be tested and certified by the vendor to run with the latest version of a database. Although it may work fine, you don’t know until it’s tested. Plus, many organizations are mandated to operate only in vendor-supported configurations. Oracle patches Oracle software comes as a base release, such as 11.0, but then you’re expected to apply patches to get a more stable and secure version, such as 11.1. These patches typically come in the form of Oracle Critical Patch Updates (CPUs), which are released quarterly (January, April, July, and October). These patches fix both software bugs and security vulnerabilities. Oracle expects you to install the base version of the software first, and then apply whatever is the most recent CPU patch (such as July CPU 2008). You don’t have to apply previous CPU patches; the fixes are cumulative, so the most recent CPU will do. Although CPUs are the most common patch, sometimes Oracle provides what are commonly referred to as one-off patches. These patches fix only a specific bug and will likely be included in a future CPU. Oracle patches are commonly applied using the OPatch (opatch) utility. This is an Oracle-provided Perl-based program that applies patches, but also runs dependency and conflict checks between your patches and can undo (roll- back) patches. This utility stores a log of all patches applied in the oraInven- tory directory located in ORACLE_BASE. opatch is a critical part of databases, and the rollback feature is great, but the wise DBA will still run a good backup of the software and databases before running any patch! Network connectivity Who is connecting to the database and how? Connecting to the database has more to it than just updating the local tnsnames.ora files with the connection information. If you’re operating in the two-tier client/server model, people will be connect- ing to the database directly using Oracle Net protocol (sometimes still called SQL*Net) and connecting on port 1521 or 1526. If you’re operating in a multi- tiered web architecture, the application server is connecting to the database on behalf of the users, probably via JDBC. The question is, are these communication ports open on the firewalls for the users or application servers to access the database? Getting firewall ports open for users requires coordination with the network staff and security, which can sometimes be an issue. 60 Part I: You Don’t Have to Go to Delphi to Know Oracle Security What security procedures must be followed before, during, and after installa- tion, and has this procedure been followed? And is there an audit trail of this? Many organizations have additional security procedures that need to be applied. You should consider these procedures before installation, as well as any impact they may have on the end product. It’s not uncommon to have to uninstall some components, lock accounts, or change file and directory per- missions after the installation. Application The database holds data, but it also contains PL/SQL packages, procedures, users, and grants/privileges to control access and processing of that data. Via SQL scripts and data loads, these objects and data must be loaded into the finished database itself. You generally have either a client-based application or a web application server that accesses the database. These components must be compiled, installed, and configured to access the database. Automated batch jobs or programs may also be part of the build process. If the application is part of a commercial package, these steps are likely well documented along with any special requirements that need to be met. In cases of a home-grown application, that documentation needs to be developed and then executed to build the application. Once done, don’t forget to test and vali- date that the system works properly before turning it over to the users. Backups No planning session would be complete if database backups weren’t consid- ered. The size and activity level of the database, sensitivity of the data, and availability and recovery requirements will drive the type and frequency of backups. In some cases, these backups take the form of traditional cold and hot backup scripts written in-house or downloaded off the web. In many other cases, you’re using Recovery Manager to schedule and run various backups. And, of course, you need to store these backups somewhere or write them to tape or other media. (For more on backup methodology, see Chapter 8.) One final note on backups: Planning and executing backups isn’t enough; you need to actually test them to ensure that they work as planned before relying on them! Part II Implementing Oracle on Your Own In this part . . . You’re ready to go. Chapter 4 leads you through the Database Creation Assistant’s help so you can make your own Oracle database. Chapter 5 gets you up and connected. If the Database Creation Assistant isn’t an option for you, Chapter 6 helps you manually build your database. Chapter 7 tells you what to populate with, no matter how you built your database. Chapter 4 Creating an Oracle Database In This Chapter ▶ Familiarizing yourself with the Oracle environment ▶ Configuring parameter files ▶ Making a database in Oracle with the DCBA It takes a lot of work to create a database. It’s true, a graphical tool called the Database Configuration Assistant (DBCA) helps you point and click your way to victory. However, as it’s named implies, it only assists. Just like any software wizard-type tool, it can’t cover every option; it can’t explain everything. It does cover up some of the ugly syntax and other required activities (like creating directories and set- ting permissions) commonly forgotten by someone new to Oracle. It truly is a wonderful tool . . . as long as you know what options to use and what values are appropriate for the questions that it asks you. With that said, this chapter goes over some of the details necessary to make the right decisions up front when creating a database. This saves you from having to go back and do things twice . . . or even three times. In addition, when you understand why you make certain choices, it helps you create a robust and scalable database that serves you for a long time to come. Feeling at Home in Your Environment You should get familiar with a few things before working in your Oracle environment: ✓ Oracle software owner ✓ Oracle version ✓ Oracle base 64 Part II: Implementing Oracle on Your Own ✓ Oracle home ✓ Oracle SID (instance/database name) ✓ Path Knowing how to find and work with these, you will better be able to manage not only your database, but databases and Oracle installations on other machines as well. If Oracle was properly installed, these items should be relatively similar across most installations. Furthermore, if they’re not similar, understanding what they are and how to find their values makes it easier for you to adapt. Some slight differences exist between Oracle installations on Windows versus a Linux/UNIX environment. We point out some of those differences as well. Finding the Oracle software owner The Oracle software owner is a user on the operating system. Linux/UNIX On Linux/UNIX you typically create a new user to own the installation files. Most commonly, this user is called oracle. In addition, you create two OS groups: ✓ oinstall should be the user’s primary group. This group will contain any users whom you would like to allow the ability to install and patch the Oracle software. ✓ dba contains any users whom you would like to have the power to manage the database in its entirety. Be very careful who you put into these groups because they could wreak havoc on your system and/or have access to all your data. Windows Windows has gone a long way to simplify running complex software on their system, and Oracle developed its software to play along. Installing Oracle on Windows only requires that the user be a member of the Local Administrators group on the machine where Oracle is installed. Consider these tips, however, which include more creation: ✓ You don’t have to create a user specifically to own the software in Windows, but we do it anyway because Oracle runs on Windows 65 Chapter 4: Creating an Oracle Database through a series of services. This way you can start those services as a specific owner. ✓ If you use the Windows task scheduler, consider using the Oracle soft- ware account to run the jobs. Jobs are easier for people to identify when they’re owned by a named account. ✓ In Windows you may sometimes want to map a drive for Oracle to use. It’s easier if you assign it to a central Oracle management account so it isn’t removed by someone else or forgotten about if passwords change. You don’t have to create any groups on Windows, but it creates a group on its own during the installation called ORA_DBA. This group behaves much the same way as the dba group on Linux/UNIX, so be careful who you add to it. Oracle versions Of course this book is about Oracle 11g. However, you may have to deal with environments that have multiple versions of Oracle installed. This version difference is especially evident when you’re upgrading your database from one release to the next. You may also encounter it when you’re testing new releases against existing applications. When you upgrade a database to the same machine, you install the new ver- sion of Oracle in parallel with the existing one. It’s important to know how to change the environments around and tell which one is active. You see how to do this on both Windows and Linux/UNIX in the following section “Sticking with the Oracle Universal Installer and oraenv.” Getting to home base On systems where Oracle is installed, an important part of managing the Oracle installation is understanding environment variables. Environment variables tell ✓ The OS what software to run ✓ Oracle where to store certain files ✓ Oracle what database you want to connect to The four most important variables are ✓ ORACLE_BASE ✓ ORACLE_HOME ✓ ORACLE_SID ✓ PATH 66 Part II: Implementing Oracle on Your Own ORACLE_BASE ORACLE_BASE is the top directory where all Oracle files on the machine are going to exist. If you have multiple versions of Oracle on the same machine, the ORACLE_BASE is likely the same. Unless you have extraordinary circumstances and want everything to stay separate, we recommend having your ORACLE_BASE be the same for all installations. A couple of common ORACLE_BASE settings follow: /opt/oracle /u01/app/oracle /app/oracle Oracle documentation uses /u01/app/oracle in most examples so we stick with that here. A few of things you should consider when setting ORACLE_BASE: ✓ Don’t install anything else under ORACLE_BASE. ✓ Choose a mount point that’s not used for any other major OS or other third-party software. ✓ The final directory in the ORACLE_BASE should be oracle. When you create your database, Oracle creates a series of directories underneath the ORACLE_BASE and uses them for management, logging, and troubleshooting. ORACLE_HOME ORACLE_HOME is where you have Oracle installed. Not only that, but it tells your session which Oracle installation you want to use. If you have multiple Oracle installations on the same machine, set this variable to the location of the one that you want to work with. Typically ORACLE_HOME values contain the major release number of the Oracle version installed in the directory. It’s created as a subdirectory off ORACLE_BASE. For example 67 Chapter 4: Creating an Oracle Database /u01/app/oracle/product/11.1.0 /u01/app/oracle/product/10.2.0 /opt/oracle/product/9.2.0 $ORACLE_BASE/product/11.1.0 The last example shows how you should use your ORACLE_BASE to define your ORACLE_HOME. ORACLE_SID ORACLE_SID is simply set to the name of the database that you want to con- nect to. If the database doesn’t exist, set it to the name of the database you’re about to create. You can change the ORACLE_SID within your session if you’re moving around to different databases. Just be very careful and note which database you’re connecting to. I’d be lying if I said the authors of this book have never made that mistake. PATH The PATH variable is typically already set for all sessions on the system. However, when you’re using Oracle, you have to add to the path. You simply have to remember to put ORACLE_HOME/bin in front of your path. ORACLE_HOME/bin is where the Oracle binaries are located. It contains tools such as the DBCA, SQL*Plus, and Data Pump. By putting ORACLE_HOME/bin in front of your path, you can execute these tools without always having to ✓ Be in the ORACLE_HOME/bin directory. ✓ Type the full path every time to want to launch a tool. The OS checks your PATH locations sequentially to find the tool you’re trying to launch. By putting your ORACLE_HOME/bin first, you guarantee not launching some other software package that has a tool with the same name as one of your Oracle tools. 68 Part II: Implementing Oracle on Your Own Sticking with the Oracle Universal Installer and oraenv All the environment settings are stored in your OS user profile on Linux/ UNIX. That way, the appropriate parameters are configured every time you log into the system to use the database. If you’re constantly switching your environment to connect to different data- bases and different Oracle versions, it might suit you to create a script where you name your different environments and then run the script and input your choice. Oracle provides a script to change the environment on Linux/UNIX installa- tions: oraenv. (Windows has no such handy little script.) You simply run the script and it asks what database you want to connect to. Then, it sets the rest of your environment accordingly. This output asks if you want to set the environment for the dev11g database. That happens to be the first database created on the machine by default. We override the default by choosing prod11g and it set the environment accordingly. [oracle@classroom ~]$ oraenv ORACLE_SID = [dev11g] ? prod11g The Oracle base for ORACLE_HOME= /u01/app/oracle/product/11.1.0/db_1 is /u01/app/oracle Oracle 9i had the Oracle Home Selector. You launched the tool from the Start Menu folder, and then clicked which version you wanted to set as your envi- ronment tool. Oracle 10g took this tool away and put the functionality into the Oracle Universal Installer. In 11g, this feature is hidden behind yet another Oracle Universal Installer screen. Here’s the secret to switching between different Oracle installations on the same machine: 1. Choose Start➪Oracle 11g Home➪Oracle Installation Products➪Universal Installer. The 11g Oracle Universal Installer launches. 2. On the first screen, click Installed Products. 3. Click the Environment tab. 4. Click the installation you want to use. 69 Chapter 4: Creating an Oracle Database 5. Use the arrow keys on the right to move that installation to the top. 6. Click Apply. Wait a few seconds. It always seems to take a too long for what it’s doing. 7. Click Close. You’re returned to the main screen. 8. Click Cancel. 9. Tell the installer that you really want to exit. Figure 4-1 shows the screen where you move the Oracle installation you want to connect to up to the top of the list. Figure 4-1: The home switch mechanism in the Oracle Universal Installer. Seems kind of lengthy, doesn’t it? We agree. If you want to accomplish the same thing without all the clicking, we recommend writing your own DOS script that works like the oraenv script. One more thing regarding Windows: All of the environment settings are also set in the registry. You can override them by setting variables from the DOS command line or by setting system-level environment variables. Of course, if you’re lucky enough to have only one environment and one database on your machine, you only have to mess with this once, when setting Oracle up. For most people, that doesn’t seem to be the case. 70 Part II: Implementing Oracle on Your Own Configuring an Instance Certain files in the database can completely change the way your database behaves. They can influence everything from performance and tuning as well as troubleshooting. Maintaining and configuring these files are a major com- ponent of database administration. Using PFILE and SPFILES These are the files that set up your database operating environment: ✓ PFILE ✓ SPFILES In Chapter 2 we talk a bit about PFILE and SPFILES. In this section we go through many of the common parameters you will find in these files that you can configure your database. The parameter file is the first file read when you start your database, so go through some of them first. First, take a look at an example of a PFILE: *.audit_file_dest=’/u01/app/oracle/admin/dev11g/adump’ *.audit_trail=’db’ *.compatible=’11.1.0.0.0’ *.control_files=’/u01/app/oracle/oradata/dev11g/control01.ctl’, ‘/u02/app/oracle/oradata/dev11g/control02.ctl’, ‘/u03/app/oracle/oradata/dev11g/control03.ctl’ *.db_block_size=8192 *.db_domain=’perptech.com’ *.db_name=’dev11g’ *.db_recovery_file_dest=’/u01/app/oracle/flash_recovery_area’ *.db_recovery_file_dest_size=107374182400 *.diagnostic_dest=’/u01/app/oracle’ *.memory_target=792723456 *.open_cursors=300 *.processes=150 *.undo_tablespace=’UNDOTBS1’ The parameters have a * in front of them because you can use the parameter file to set parameters in more than one Oracle instance. In a file that serves multiple Oracle instances, you may see the instance name in front of some of the parameters, denoting that particular parameter only applies to one instance. 71 Chapter 4: Creating an Oracle Database Follow these steps to see the parameters that are modified in your existing Oracle database: 1. Log into SQL*Plus as a SYSDBA. 2. Type create pfile from spfile; (including the semicolon). The command dumps a text version of your SPFILE. Once you create your PFILE, you want to turn it into an SPFILE. Essentially, you do the reverse of what you did before: 1. Log into SQL*Plus as a SYSDBA. 2. Type create spfile from pfile; (including the semicolon). You get a file called spfileORACLE_SID.ora in the same directory as your PFILE, where ORACLE_SID is your instance_name. Setting parameters in the pfile and spfile Whether you use PFILES or SPFILES determines how you set your param- eters. This next section explains the common parameters in Oracle 11g and how they’re configured in the files themselves. With a new database, you always start with a PFILE. If you end up wanting to use an SPFILE, you create it from the PFILE (shown at the end of the chapter). The first thing you need to do is find your PFILE. For whatever reason, despite all the other similarities, Linux/UNIX and Windows store it in different locations. Find your PFILE on Windows, where ORACLE_SID is your instance name: ORACLE_HOME\database\initORACLE_SID.ora Find your PFILE on Linux/UNIX, where ORACLE_SID is your instance name: ORACLE_HOME/dbs/initORACLE_SID.ora These parameters are some of the most commonly customized. Most param- eters suit most databases at their default value. The * means to apply the parameter to all instances that read this file. 72 Part II: Implementing Oracle on Your Own ✓ audit_file_dest: This parameter tells Oracle where to put auditing infor- mation on the file system. All connections to the database as SYSDBA are audited and put into this directory. Furthermore, if you’re auditing other operations in the database, those audit records may be dumped here as well. ✓ audit_trail: This tells Oracle where you want audit records written. Audit records can be written to the database or the file system. They can be in text format or XML. Records written to the database are stored in the AUD$ system table. The valid values for this parameter follow: • db: Normal audit records written to the AUD$ table • os: Normal audit records written to the audit_file_dest directory • db_extended: Audit records written to the AUD$ table in extended format, including SQLTEXT and bind variable values • xml: XML-formatted normal audit records written to the database • xml, extended: Normal auditing and includes all columns of the audit trail, including SqlText and SqlBind values in XML format to the database ✓ compatible: Set it to force the database to behave like a version ear- lier than Oracle 11g. In Oracle 11g you can set it back as far as 10.0.0. However, it can only be set back before the database is created or before upgrading from an earlier version. Once you migrate this param- eter to 11.1.0 and open the database, you can no longer go back. The parameter’s useful for testing before an upgrade is complete. Most of the time you find it set on the latest version for your software. If you try using a feature from a database version later than what you’ve config- ured, it results in an Oracle error. ✓ control_files: Just what is says. It tells the instance where to look for the control files during the startup phase. If the instance doesn’t find even one of them, you can’t mount your database. Notice in the parameters listing that the controlfiles are spread across three different mount points. ✓ db_block_size: This parameter is really the only you can’t easily change without recreating the database, so choose it carefully. It tells the data- base what block size you want your Oracle blocks to be formatted on disk. We discuss this more later on in the chapter. ✓ db_domain: If you want your network domain to be part of your data- base name for identification purposes, fill in the domain name here. This won’t be your actual database name, but an alias to identify it from other databases with the same name that might exist in another domain. 73 Chapter 4: Creating an Oracle Database ✓ db_name: The database name. Think about this carefully. While it can be changed, it’s a pain. The name can be up to eight alphanumeric char- acters. Avoid the urge to use special characters other than #, $, and _. ✓ db_recovery_file_dest: This sets what’s known as the flash recovery area. The area can hold files such as • Backups • Archive log files • Control files • Redo log files We use it a lot for the first two tasks. While it can be done, to us it doesn’t make sense to put redo and control files in here. ✓ db_recovery_file_dest_size: This determines how much space is dedi- cated to your flash recovery area. If it fills up, you get an error message and the database could come to a halt — especially if you’re storing archive log files here. If archive log files can’t be written, redo log files can’t be overwritten. User sessions hang until the situation is resolved. ✓ diagnostic_dest: This location is known as the Automatic Diagnostic Repository (ADR) home. It contains files that Oracle Support may use to resolve issues with your database. This 11g parameter is new. You can use a new tool called ADRCI to access the files in this directory. It contains • Trace files • Core files • Alert logs • Incident files ✓ memory_target: This parameter sets the memory that the Oracle instance is allowed to use for all system global area (SGA) and program global area activities described in Chapter 2. It doesn’t include memory consumed by server and user processes. ✓ open_cursors: Limits the number of open SQL cursors a session can have. ✓ processes: Limits the number of OS users’ processes that can connect to the instance. ✓ undo_tablespace: This parameter tells the instance to which tables it will write its transaction undo. It must be an undo type tablespace. 74 Part II: Implementing Oracle on Your Own Creating Your Oracle Database You can create a database one of four ways: ✓ Manually with SQL commands. If you’re on an ancient release like Oracle 8i, we recommend manual SQL commands; the DBCA wasn’t as good back then. However, with Oracle 9i and up, it has really become a robust and useful tool. Furthermore, with more features being added to the data- base, the manual method isn’t a laundry list of scripts. Back in the day you only had to run an SQL command and two scripts. Not anymore. ✓ With the graphical tool called Database Configuration Assistant (DBCA). We recommend Database Configuration Assistant (DBCA) to make your Oracle database. This is especially true for beginners. If you use DBCA to create the database, you don’t have to make the PFILE; the DBCA creates it for you. You may want to alter your setting later, however. ✓ A combination of SQL commands and DBCA. Even old-timers like us prefer DBCA or SQL and DBCA. Using SQL to create the database gives you control over every aspect of the creation, but it also leaves open a lot of areas for mistakes and accidental omissions. ✓ Cloning an existing database. This book doesn’t cover the topic because it’s a more advanced topic for, uh, smarties? Bossing the Database Configuration Assistant (DBCA) Launch the Database Configuration Assistant (that’s right; you’re in charge) from the command line of the operating system where the database resides. This set of steps chooses the Custom Database option (versus General Purpose or Data Warehouse options). This option is for when you really want to get your hands dirty and have complete control. We like this option. ✓ You don’t have to install the features that you aren’t going to use. They just take up more space and give you more things to manage. ✓ You can specify a lot more options that the other templates don’t allow. ✓ Customizing isn’t that hard. You’re reading the book, right? It’ll be easy. 75 Chapter 4: Creating an Oracle Database The only drawback to the Custom Database method is the time it takes while creating the data files. How much time? We’ve seen it take anywhere from 2 to 30 minutes. It depends on ✓ The number of CPUs ✓ What features you select Taking database control Database control is an option you can choose during database creation. Don’t get too attached to this invaluable resource. Take some time to learn the basic SQL commands for managing your database. I’ve seen Database Control crash and the only thing left was a blinking SQL prompt. A well-rounded DBA knows how to manage her database both ways. Under the Database Control section you’re asked whether you want to enable alert notifications. This is valuable on a production database, but I wouldn’t enable alert notifications ✓ If you’re just installing this for testing purposes ✓ On a production database until I configured what things I wanted alerts for; otherwise you’re deluged with all kinds of frivolous alerts Next, it asks if you want to enable automated backups of your system to disk. Again, if this is a test environment, you may not want to bother with this. After some time, your machine will probably start running out of space. Backups aren’t always necessary in a test environment. Furthermore, even if this is a production database, I might wait until everything is in place before I start backups. We go over this extensively in Chapter 8. DBCA steps Not only does this tool create databases, it lets you delete and modify them, create database templates, and set up a feature called Oracle Automatic Storage Management. Notice at the top in the title bar it says 1 of 15 steps. We kid you not that in Oracle 9i it was 1 of 8 steps and in 10g it was 1 of 12 steps. This is what we mean: Creating the database with the DBCA is the way to go as Oracle gets heavier with features. 76 Part II: Implementing Oracle on Your Own Taking the DBCA steps If you’re ever unsure about an option on the DBCA screen, click the Help button. It does a pretty good job of explaining what each thing does. One of the things we have noticed in Oracle 11g is that Oracle has done a good job of speeding up the Help function. In past versions it took forever to load. Try it out! The DBCA has a lot of screens with all kinds of information. The following steps take you through creating a database with the Database Configuration Assistant. 1. Log in as the Oracle software owner. 2. Go to a command prompt. 3. Type dbca. You see the welcome screen shown in Figure 4-2. 4. Click Next. You see another screen with several options. Figure 4-2: The Database Configuration Assistant welcomes you. 5. Click Create a Database. 6. Click Next. This time you see the output shown in Figure 4-3. Optional database templates are shown: 77 Chapter 4: Creating an Oracle Database • General Purpose • Data Warehouse • Custom Database The first two include the data files. You supply a few custom settings and it unzips the database from the Oracle installation directory. Use these options only when you’re new to Oracle and aren’t sure what to do with some of the more advanced parameters. You should choose Custom here; we go over all the options in the rest of the steps. 7. Choose Custom Database. Figure 4-3: Database creation options require lots of steps. Click Show Details if you want to see the features, parameters, and files chosen by default for each type of database. 8. Click Next. A screen asks you to choose the database name. 9. Fill in these fields: • Global Database Name. Your database name with your network domain attached. If you don’t want to attach your network domain, leave this field blank. Doing so just sets the initialization param- eter db_domain. It helps uniquely identify your database on the network. For example, you might have a database named prod in two different domains. A global database name allows that without confusing some of the Oracle networking features. • SID. This is the short name for your database. It equates to your environment variable ORACLE_SID. 78 Part II: Implementing Oracle on Your Own 10. Click Next. A screen asks if you want to manage your database with Enterprise Manager. See the output in Figure 4-4 and read more about Oracle Enterprise Manager in Chapter 13. Figure 4-4: Your database management options come here. It can be configured two ways: • Register with Grid Control for Centralized Management: An Oracle software package that typically runs on its own server elsewhere on your network. It can manage many databases, many versions of Oracle, servers, application servers, and even other non-Oracle software such as Microsoft SQL server and firewalls. You must have the Grid Control Management Agent installed to get this option. • Configure Database Control for Local Management: Database control is a management package that runs locally on the database machine and has many of the features of Grid Control. However, it only controls one database. We only caution you when configuring Database Control. If you’re setting Oracle up on a machine with limited resources, you’re going to feel Database Control, if you know what we mean. 11. Choose Database Control. Choose Database Control as your management option only if you’re comfortable with your machine’s resources. You can always stop when you’re not using it and start it later. 79 Chapter 4: Creating an Oracle Database If you see the error message because you haven’t set up Oracle’s lis- tener network process (described in Chapter 5), open a prompt to the operating system as the Oracle software owner and type lsnrctl start. Eventually you see The command completed successfully and get your prompt back. 12. Click OK and then click Next. It works this time. The next screen asks about passwords. Automatically included users are DBA users and users for Database Control. 13. Decide on passwords. • Use different password for each user. If this is a test database, it may not matter that much. Even if you want to keep it simple now and make all the passwords the same, you can easily go back change them later. • Set the same password for everyone. If this is production, it’s in your best interest to have separate passwords for all the users. 14. Click Next. The following screen asks how you want to store your files: • File System. All your data files are put into formatted drives attached to your computer. • Automatic Storage Management (ASM). Don’t choose this now. ASM has some great benefits but isn’t as easy to set up as the DBCA leads you to believe. • Raw Devices. They’re tough to back up and restore when prob- lems arise. We aren’t saying, “Don’t use them.” Just don’t use them right now. 15. Choose File System and click Next. You’re asked where you want the files stored and what to name them. Really, you’re given one location. 16. Choose a place to store your files: • File Locations from Template. This option doesn’t let you make any changes. Oracle chooses where to put the files. • Common Location. This option activates the grayed-out field. You choose type or browse for a location to store the files. • Oracle Managed File. You decide where to put files. You can’t change the file names until after database creation. Oracle names them for you. Separating files across multiple mount points is a best practice for performance and protection. If you create a test database or other non- production database, it’s okay to put them all in one place if you have the space. 80 Part II: Implementing Oracle on Your Own 17. Choose File Locations from Template and click Next. You’re in the Flash Recovery Area (FRA) configuration. The FRA is a storage area that resides on disk which can house backups, archive logs files, control files, and redo log files. 18. Choose to configure the FRA. Doing so simplifies the storage of backups and archive log files. We typically use it for the control or redo. We manually separate those ourselves. 19. Determine what FRA space you have available and increase it accordingly. The default value is about 2GB. This might be okay for the archive log files of small databases. However, an FRA of this size will fill up very quickly. You can resize the FRA anytime without taking the database down. 20. Choose to archive later and click Next. It adds drain on the system while creating the database. It’s easy enough to enable later on. You’re asked what features you want to install on the screen. Depending on what software you installed, not all are available. Luckily, you can add later. Click the Help button if you want a more detailed description: • Oracle Text: This indexing feature allows custom indexing of large text-type documents. It can index pages of data. It also allows advanced searching against rich media objects. • Oracle OLAP: This is Oracle’s business intelligence tool. • Oracle Spatial: This mapping tool is for geospatial mapping. • Oracle Ultra Search: Text-only indexing and searching mechanism. Filing that away We could buy the argument that it’s okay to put files in the same location if later on you were going to separate your application data files accordingly. Also, it’s relatively easy to move them. The other possibility is that you’re going to use a large chunk of storage on a SAN (a high-speed storage area network) that pres- ents its storage to you as one location, and then manage the performance in the background by spreading the files across many disks. 81 Chapter 4: Creating an Oracle Database • Oracle Label Security: Label security is for securing data in a way that gives users levels of access to restricted data. • Sample Schemas: This bunch of test data that you can use for training or trying new features. We usually install this on test and training databases. It includes several schemas with varying degree of complexity. • Enterprise Manager Repository: Just like it says, install this if you want to use Enterprise Manager Database Control with your data- base. If you’re going to use Grid Control, leave this out. • Oracle Warehouse Builder: Data warehouse tools for developing corporate metadata and consolidating data from various sources. • Oracle Database Vault: Basically this locks down the database to extreme measure, disallowing activities we take for granted in a normal system. It protects your database against your own people, in essence. It significantly creates more management overhead. However, in a system that must remain ultra-secure, it’s the price you pay. • Oracle Database Extension for .NET: If you’re going to develop Microsoft .NET apps to run against your database, this suite of utilities helps you integrate better with .NET’s features. 21. Click the Standard Database Components button and choose what you want installed: • Oracle JVM: Oracle Java Container for running Java out of the database. • Oracle XMLDB: Contains XML extension for the database to better integrate with XML applications. • Oracle Multimedia: Extends Oracle’s capabilities to offer better support for multimedia data. • Oracle Application Express: This is the kind of a development environment that allows you to develop applications in a web- based framework. It runs on top of the database and allows creat- ing hosted applications that can be quite robust. If you’re testing to get a basic environment up and running, deselect everything. However, if you’re going to work with one or more of these options, install them. Remember that they take space and time during the database creation process — some more so than others. 22. Click Next. Figure 4-5 shows the screen where you begin choosing the initialization parameters discussed earlier in the chapter. The Memory tab has two options: Typical and Custom. 82 Part II: Implementing Oracle on Your Own Figure 4-5: Choosing database initialization parameters. 23. Choose Typical. Since we’re talking Oracle 11g, choosing Typical sets the memory target as one large chunk and lets Oracle figure out where everything goes. 24. Click the Sizing tab. 25. Choose the block size. If you get this wrong, your only option is to re-create your database (if the performance problems haven’t gotten you fired). • If you’re creating a database that will have many users with smaller quick transactions, go with a block size of 4k. • If you’re creating a data warehouse-type database with large SQL queries that retrieve heaps of data at once for analysis, choose the largest block size you can. The largest block size you can choose is OS dependent. • If you’re somewhere in the middle of the first two, go with 8k. • Make sure the block size is divisible evenly by the OS block size or OS I/O size. You don’t want your OS to read a minimum of 8k but choose a 4k block size. That would waste 4k for every read. 26. Click the Character Set tab. You can change the character set after creating the database, but it’s time consuming and tedious. Choose a character set that will house all the characters that your application may use. • Database Character set. For all the standard-language columns in your database. Also encompasses the character set that Oracle messages will display in, and the characters you may use in program code. 83 Chapter 4: Creating an Oracle Database • National Character set. For special datatypes that may house data only used in your applications. For example, what if you work at a primarily English-speaking university and the Greek department wants to create an application to storage indexable, searchable Greek manuscripts? No programming or database message will be displayed in Greek. • Unicode Character sets. Choose this if you’re going to support multiple languages. 27. Click the Connection Mode tab. • Dedicated Server Mode • Shared Server Mode We discuss this in Chapter 2. Most current systems use dedicated server connections. In most cases we recommend starting that way. If memory is constantly running short (while at the same time supporting thou- sands of users), investigate shared server configuration. The All Initialization Parameters button lets you adjust all parameters discussed earlier in the chapter (as well as others we didn’t); see Figure 4-6 for the All Initialization Parameters screen. By default the screen shows only what Oracle considers basic parameters. Oracle considers some parameters advanced. You don’t need them but if you’re curious, click Show Advanced Parameters. 28. Choose a security option: Figure 4-6: The All Initialization Parameters page lets you make adjust- ments. 84 Part II: Implementing Oracle on Your Own • Keep the enhanced 11g default security settings (recommended) if you want to take advantage of 11g’s advanced security settings such as turning on auditing by default and enforcing stronger password. • Revert to pre-11g default security settings and have very little password security and no auditing. The 11g security profile enables more auditing by default and enforces more secure passwords. It makes passwords case sensitive. 29. Breathe. You’re almost done. 30. Choose Yes to automate certain maintenance tasks in the database. If you choose Yes, Oracle automatically gathers performance-related statistics on your objects to speed up query execution. If you don’t auto- mate the tasks, you have to do them manually. 31. Make storage adjustments. Now is a good time to make sure the files spread across multiple mount points. Click each menu: Controlfile, Tablespaces, Datafiles, and Redo Log Groups. Change the directories (on the right) so they’re not all in the same place. As you can see in Figure 4-7, the left pane lists the file and storage objects. The screen currently shows the Controlfile choices. Figure 4-7: The storage configura- tion page lists file and storage objects. About file locations: In the past, we’ve encountered problems with some directories not being there when you change where the files are created. Sometimes Oracle complains about permissions. 85 Chapter 4: Creating an Oracle Database Make sure the permissions on the directories where you store your files are set for the Oracle user to read and write. For example, if you move a control file to /u01/oradata/dev11g and that directory isn’t there, some systems give an error and the database creation stops. We create all the directories where files are going to go ahead of time. This might resolve some headaches when you launch the actual data- base creation. 32. Decide if you want to create the database now. 33. Click Next to start creation. 34. Decide if you want to save your decisions as a template for future use. If you think you may create a similar database again, this might be a good idea. You can give it a name and a description. 35. Save everything you did in a set of scripts and decide where you want them. It’s a good idea to keep these around just in case. Also, if you’re curious about all the scripting work you just avoided by using the DBCA, have a look. 36. Click Finish. A screen shows all the options you just chose and the parameters you set. 37. Decide if you want to save your choices as a file. If you do, the DBCA creates an HTML file summarizing your configura- tion. Then it starts creating the database. First, the template is made (if you chose one in Step 33); you also see the script creation screen (if you chose to save the creation as scripts in Step 34). 38. Click OK to acknowledge the template and script screens. The creation status screen appears. A status bar and options also appear. You can watch it go through everything until it’s done. Once the database is complete, a screen shows the details. A Password Management button lets you unlock or change the passwords of the users that were created as part of the options you installed. All users except SYS, SYSTEM, DBSNMP, and SYSMAN are locked. If you installed the sample schemas, this is a good place to unlock them and reset their passwords. 39. Click Exit to close the DBCA. 86 Part II: Implementing Oracle on Your Own Sharing (a) memory Personally, we think a “typical” memory option is a bit of a misnomer. Nothing is typical about memory settings. It all depends on ✓ How much you have ✓ How many databases are going to be on the machine ✓ How many users you’re expecting ✓ How much memory your users are going to require Also, it is quite common to give yourself a starting point and then go from there. You see that Oracle suggests using 40 percent of your memory for the shared and private areas of your database. This is an interesting choice. What if this machine were destined to house ten databases? Hmmm.… Think about how the memory on this machine is going to be shared. These points might help you decide: ✓ Never start with the combination of shared and private memory areas of all your databases on the machine consuming more than half the memory. Therefore, if you have 8GB of memory and there will be two databases, both memory_target parameters combined shouldn’t exceed 4GB. This gives plenty of room for error. ✓ If your database is going to be extremely large, figure out how many users will have server sessions at once. Take that number and multiply by 5MB. Add 2GB for your OS and then add 20 percent more of the avail- able memory. Split what is left over amongst the rest of the databases. This still might not be right for you, so Chapter 11 discusses tuning and performance management. Ultimately, the memory you need boils down to monitoring and adjusting. We wanted to give you a starting point. It is one of the most common user questions yet is difficult to quantify without real application environment data. 10g Memories If you were on Oracle 10g, the Custom option on the Memory tab gives you a choice. You can set separate shared and private areas. It still gives you the typical 40 percent option, but it then sets the two in the background. If you were back in Oracle 9i, you’d have to set all the memory areas yourself. Man, how did we get by back in 2001? If you want to set everything your- self, or you want to see what it looked like in 9i just for the fun of it, select Custom and change the drop-down list to Manual Shared Memory Management. Ah the memories . . . . 87 Chapter 4: Creating an Oracle Database Feeling the Post-Configuration Glow When everything is complete, you might want to log into your database for the first time and check everything out. ✓ Look in the directories where the files were supposed to go. ✓ Check your initialization parameters. ✓ Perform a backup if this is a soon-to-be production database. That way you don’t have to create the entire database again if something goes wrong. 88 Part II: Implementing Oracle on Your Own Chapter 5 Connecting to and Using an Oracle Database In This Chapter ▶ Starting and stopping the database ▶ Connecting to the database instance ▶ Avoiding pitfalls You can’t use a database until it’s running and you connect to it. In this chapter we cover how to make that happen. First, we cover the setup of your DBA environment so you can log in to the database and begin your startup work. Next, we cover the various startup modes and states that a database can be in depending on your type of work. Furthermore, shutting down a database can happen several different ways. We cover all the options so that you can start up and shut down with the proper parameters. You can connect locally or remotely to a database with Oracle Net. We exam- ine the role of the database listener process and how to configure, start, and stop it. Next, we show how to set up client-side connections to the database. Finally, we cover a few common problems you might encounter when setting up Oracle Net. Starting and Stopping the Database Before users connect to a database instance to do work, it obviously must be running. This entails starting up the database instance memory, processes, and opening the control and database files in a mode accessible and appro- priate for the users. Depending on the type of work being done, there are several different states a database can be in for the users or DBA to access. Alternatively, it is sometimes necessary to shut down a database instance for a multitude of reasons. The key with shutdowns are what happens to users logged in and doing work when the shutdown occurs? Several different ways exist to handle existing users and the state of their work. 90 Part II: Implementing Oracle on Your Own Environmental requirements Before starting or stopping an Oracle database instance, a few environmental requirements must be met. These environment requirements get you logged into the server as the correct user with the right environment variables so that you can do your DBA work. Log in to the database server Log in to the server where the database resides to do your key database administrator (DBA) work. Yes, you can do some of this via Enterprise Manager but only after you’ve set up your environment and created your database in the first place. Most critical DBA work occurs on the database server itself because it pro- vides the most flexibility and is the simplest for starting DBAs. Log in as the Oracle DBA account You should be in the operating system DBA account that owns the Oracle software to start and stop the database. Commonly this is the oracle user account and is in the DBA group: $ id uid=501(oracle) gid=501(oinstall) groups=501(oinstall),502(dba)) The oracle user is in groups oinstall and dba. Set up your environment variables Many environment variables exist for your oracle user and we cover them in detail in Chapter 4. However, at a minimum you want to have these variables set: ✓ ORACLE_BASE ✓ ORACLE_HOME ✓ ORACLE_SID $ echo $ORACLE_BASE /u01/app/oracle $ echo $ORACLE_HOME /u01/app/oracle/product/11.1.0/db_1 $ echo $ORACLE_SID dev11g 91 Chapter 5: Connecting to and Using an Oracle Database Be sure to verify the ORACLE_BASE, ORACLE_HOME, and ORACLE_SID vari- ables before you do any type of DBA work. It is very easy to define the wrong ORACLE_HOME, in which case you work with the wrong database software. Worse yet, it’s even easier to incorrectly define ORACLE_SID and stop the wrong database! If it occurs frequently, you’re making what we refer to as a “career-limiting move.” Start SQL*Plus as a DBA The command-line interface into Oracle databases is SQL*Plus. To do serious DBA work such as startup or shutdown, you need to be logged in as SYSDBA. To log in this way, you must be the oracle operating system user as described earlier in this chapter. Then start SQL*Plus with the “/ as sysdba” option: $ sqlplus “/ as sysdba” SQL*Plus: Release 11.1.0.6.0 - Production on Wed Sep 24 07:46:53 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SYS@dev11g> An alternative: Once you’re in SQL*Plus, issue connect as sysdba to log in as SYSDBA, provided you’re on the database server as the oracle operating system user. SYS@dev11g> connect / as sysdba Connected. SYS@dev11g> Once connected as SYSDBA, you can begin your DBA work. Database parameter file Before starting the database, you must have a parameter file listing all the different runtime parameters, such as SGA configuration. This is covered in detail in Chapter 4, so we won’t rehash the details here. However, we assume you have your SPFILE created and in a default location so that Oracle can find it. If it isn’t in a default location, or you want to use a different parameter file, you may use the pfile=’’ syntax with your startup commands. 92 Part II: Implementing Oracle on Your Own Improper environment setup is a common error and is something you should verify before beginning your database work. Doing so will save you time and frustration troubleshooting unnecessary errors. Starting the database You don’t actually start a database per se; you start the instance. A database is defined as the actual data, index, redo, temp, and control files that exist on the files system. The instance consists of the processes (PMON, SMON, DBWR, LGWR, and others) and the SGA (memory pool) that access and process data from the database files. The instance is what accesses the database, and it is the instance that users connect to. Thus, it is the instance (not the database) that you actually start. Are we splitting hairs here? Not in this case; you need to understand the rela- tionship between the instance and the database to understand startup and shutdown. As an Oracle instance starts, it proceeds through various states until it and the database are fully open and accessible to users. At each state, different components are started and opened. Furthermore, at each state you may per- form different types of DBA or user work. You may specify your startup com- mand to take the database instance into a specific state depending on what you need to do. In ascending order, during startup the database instance goes through these states: NOMOUNT ✓ Read Parameter File ✓ Allocate SGA ✓ Start Background Processes ✓ Only SGA and Background Processes Running ✓ Used for CREATE DATABASE (Only SYS can access) ✓ Specified by STARTUP NOMOUNT 93 Chapter 5: Connecting to and Using an Oracle Database MOUNT ✓ Read Parameter File ✓ Allocate SGA ✓ Start Background Processes ✓ Open and Read Control File ✓ SGA and Background Processes Running and Control Files Open ✓ Used for database maintenance and recovery operations (Only SYS can access) ✓ Specified by STARTUP MOUNT OPEN ✓ Read Parameter File ✓ Allocate SGA ✓ Start Background Processes ✓ Open and Read Control File ✓ Open All Database Files ✓ SGA and Background Processes Running, Control Files Open, All Database Files Open ✓ Default OPEN state for database and is accessible by users and applications ✓ Specified by STARTUP or STARTUP OPEN Unless you’re performing specialized maintenance, the default is as follows: ✓ STARTUP with the parameter file read ✓ Background processes and SGA started ✓ Control files open and read ✓ All database files open In this open state, users access the database normally. Here’s what it looks like when starting the database into the default OPEN mode. Because we’re using the default parameter file, we don’t need to specify one. 94 Part II: Implementing Oracle on Your Own $ sqlplus “/ as sysdba” SQL*Plus: Release 11.1.0.6.0 - Production on Sat Sep 27 02:58:05 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. Connected to an idle instance. SYS@dev11g> startup ORACLE instance started. Total System Global Area 789172224 bytes Fixed Size 2148552 bytes Variable Size 557844280 bytes Database Buffers 218103808 bytes Redo Buffers 11075584 bytes Database opened. SYS@dev11g> Although we normally go straight to the fully open mode, you can increment the modes. For example, you could do database maintenance with the data- base in MOUNT mode and, once done, issue ALTER DATABASE OPEN to take the database to open mode so users can start work. That’s what’s done here: SYS@dev11g> startup mount ORACLE instance started. Total System Global Area 789172224 bytes Fixed Size 2148552 bytes Variable Size 570427192 bytes Database Buffers 205520896 bytes Redo Buffers 11075584 bytes Database mounted. SYS@dev11g> alter database open; Database altered. SYS@dev11g> Note that you can only go forward to a more open state; you can’t move to a more restrictive state without issuing a shutdown. In most cases when you open a database, you want it open for every user. Sometimes, however, you want to block all or some users even though the database is in OPEN state. 95 Chapter 5: Connecting to and Using an Oracle Database To do this, put the database in RESTRICTED SESSION mode via one of these ways: ✓ STARTUP RESTRICT ✓ ALTER SYSTEM ENABLE RESTRICTED SESSION SYS@dev11g> startup restrict; ORACLE instance started. Total System Global Area 789172224 bytes Fixed Size 2148552 bytes Variable Size 570427192 bytes Database Buffers 205520896 bytes Redo Buffers 11075584 bytes Database mounted. Database opened. SYS@dev11g> SYS@dev11g> alter system enable restricted session; System altered. ✓ When the database is OPEN, you must grant users CREATE SESSION to connect. ✓ When the database is RESTRICTED, users must have CREATE SESSION and they also must have RESTRICTED SESSION to connect. The only backdoor is if the user was already logged in when an ALTER SYSTEM ENABLE RESTRICTED SESSION was issued; then the user can remain logged in. Therefore, you should kill all user sessions after putting the database in RESTRICTED mode to kick them out. If they don’t have RESTRICTED SESSION, they get this Oracle error when they try to log in: $ sqlplus barb/test123 SQL*Plus: Release 11.1.0.6.0 - Production on Sat Sep 27 03:17:46 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. ERROR: ORA-01035: ORACLE only available to users with RESTRICTED SESSION privilege Why would you want to do this (other than just to frustrate your users)? While frustrating users is the secret pleasure of every administrator (espe- cially security administrators), some valid technical reasons exist. Major 96 Part II: Implementing Oracle on Your Own data, table, or application updates often need a stable system with no updates or locks to contend with so they can process successfully. Some database maintenance operations also require restricted session. If you need to allow in a subset of users or perhaps the application user pro- cessing a database job, you may grant them RESTRICTED SESSION: SYS@dev11g> grant restricted session to barb; Grant succeeded. SYS@dev11g> connect barb/test123 Connected. Revoke the RESTRICTED SESSION from any non-DBA user once the user’s work is done. Also, don’t forget to take the instance out of restricted session. SYS@dev11g>alter system disable restricted session; System altered. Starting up database instances isn’t terribly difficult and most times you use the default STARTUP command to take the database instance to the OPEN state. Only occasionally does the situation require a RESTRICTED SESSION. If the database startup seems to take a few minutes, it may be because of a large SGA during which time memory is being allocated. Or there may be many database files to open. If the database crashed or a SHUTDOWN ABORT occurred prior to the startup, database instance recovery is occurring, which can take time. If this occurs, leave your screen with the STARTUP command open; let it run. View the alert log with another window. We cover the alert log in Chapter 12. If more severe errors occur (such as media recovery), they appear both on the startup screen and in the alert log file. Of course, you can prevent much of this if you stop the database in a clean manner. Carry on to the next topic. Stopping the database Just as there is an order of events to starting a database instance, there is also an order for how a database instance is stopped. Ideally, this is what happens during a database shutdown: ✓ New connections to the database are denied. ✓ Existing transactions are either committed or rolled back with proper updates to online redo log files. ✓ User sessions are terminated. 97 Chapter 5: Connecting to and Using an Oracle Database ✓ Database file headers are updated and files are closed. ✓ SGA is shut down. ✓ Background processes are terminated. It is preferable for all the steps to occur naturally during shutdown. That ensures that ✓ All transactions are neatly committed or rolled back. ✓ Online redo log files are properly updated. ✓ All files are closed properly without corruption. If the preceding steps don’t occur during shutdown because of a server or database instance crash or SHUTDOWN ABORT, the cleanup operations must occur during startup in a phase called instance recovery. During instance recovery, Oracle won’t open a database instance until it’s satisfied that all transactions are accounted for and all data files are opened. If it can’t complete these tasks, error messages appear and the DBA must address them. Instance recovery is successful most of the time, but it may take several minutes to process the cleanup. Shutdown types When a database needs to be shut down, several methods exist to do so with varying effects on current users and their transactions. SHUTDOWN [NORMAL] ✓ New connections to the database are denied. ✓ Existing transactions continue normally until either they roll back or commit. ✓ Users log out normally on their own. ✓ After the last user logs out, database file headers are updated and files are closed. ✓ SGA is shut down. ✓ Background processes are terminated. ✓ Specified by the SHUTDOWN or SHUTDOWN NORMAL command. SHUTDOWN TRANSACTIONAL ✓ New connections to the database are denied. ✓ Existing transactions continue normally until either they roll back or commit. 98 Part II: Implementing Oracle on Your Own ✓ After an existing transaction is completed, user sessions are terminated. ✓ Database file headers are updated and files are closed. ✓ SGA is shut down. ✓ Background processes are terminated. ✓ Specified by the SHUTDOWN TRANSACTIONAL command. SHUTDOWN IMMEDIATE ✓ New connections to the database are denied. ✓ Existing transactions are rolled back. ✓ User sessions are terminated. ✓ Database file headers are updated and files are closed. ✓ SGA is shut down. ✓ Background processes are terminated. ✓ Specified by the SHUTDOWN IMMEDIATE command. SHUTDOWN ABORT ✓ New connections to the database are denied. ✓ Existing transactions are not rolled back. ✓ User sessions are terminated. ✓ SGA is shut down. ✓ Background processes are terminated. ✓ Specified by the SHUTDOWN ABORT command. ✓ Instance recovery is required on startup. Shutdown decisions When do you use each shutdown type? ✓ Generally, SHUTDOWN IMMEDIATE is what you want because it cleanly commits or rolls back existing transactions, terminates user sessions when they are complete, and then closes the database in a clean manner. ✓ Don’t use SHUTDOWN NORMAL very often because even one user still logged in (after he’s left for the day) can hang the shutdown. 99 Chapter 5: Connecting to and Using an Oracle Database ✓ SHUTDOWN TRANSACTIONAL doesn’t buy you much because it forces you to wait on users to finish their transactions. If you want to wait, you can just enter SHUTDOWN NORMAL. However, if you want to force them off the database instance, you use SHUTDOWN IMMEDIATE. There are times SHUTDOWN TRANSACTIONAL is useful, but it’s not as common as you might think. Here’s how a typical SHUTDOWN IMMEDIATE executes. Keep in mind that you must be logged in as SYSDBA to run the shutdown command. SYS@dev11g> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SYS@dev11g> exit ✓ Only use SHUTDOWN ABORT when you have to. It essentially crashes the database and expects instance recovery to pick up the pieces. You may have to do that if the system is hung, but it shouldn’t be your first choice (unless you want to do real database recovery sometime). If you are able to issue commands on the database instance, issue an ALTER SYSTEM SWITCH LOGFILE to force a checkpoint to close file headers and flush the online redo logs before issuing the SHUTDOWN ABORT. Forcing a check point will allow for an easier instance recovery during the next startup. Connecting to the Database Instance A database instance isn’t much good if you can’t connect to it. Establishing a reliable, persistent, and secure connection to the database from the client is essential. Oracle has established a network architecture of protocols, processes, utili- ties, and configuration files to support communication into the database. Oracle Net (formally called SQL*Net or Net8) is Oracle’s networking protocol. Oracle Net is supported by ✓ DBA-managed listener processes ✓ Client- and server-side configuration files ✓ Command-line utilities ✓ Optional GUI administration tools 100 Part II: Implementing Oracle on Your Own Additionally, connections can come into the database via several lighter- weight non-Oracle protocols such as ODBC or JDBC. However, even these non-Oracle protocols use the same underlying server-side Oracle compo- nents as Oracle Net connections. For these reasons, we focus on the Oracle specific components. Local versus remote connections Connections into the database can be one of two kinds: ✓ Local (bequeath). A local connection originates from the same server the database is on and doesn’t use the database listener process. When you connect to SQL*Plus as “/ as sysdba”, you’re connecting locally. ✓ Remote. All other connections from outside the database server or those from the server using the listener are remote connections. The easy way to determine if a user is connecting remotely is if you have @TNS_ALIAS in the connect screen. For example, sqlplus scott@ dev11g indicates a remote connection to the dev11g database. Communication flow Connections to an Oracle database typically come across from a client located away from the database, over a network infrastructure, to the data- base server, through a database listener process and, finally, into the data- base itself. On the client side, the program calling the database references tnsnames. ora to find the database server host and protocol to send the request to. The request then leaves the client and goes onto the network utilization Oracle Net. The standard port for Oracle Net communications is either 1521 or 1526, although that’s configurable. Over this Oracle Net protocol is where database communications traffic flows between the client and database server. After a client’s communication request reaches the database server host, it’s handed off to the listener. The database listener is a separate Oracle software process on the database server that listens for incoming requests on the defined Oracle Net port (1521 or 1526). When it gets a request, the listener identifies which database instance is targeted for that request and establishes a connection to that database instance. On the server side, the listener uses the listener.ora file to make this determination. When the con- nection is established and the session begins, the listener steps out of the picture and allows communication between the database and client. Each client session has a dedicated server process on the server side. Within this dedicated server process, the user’s session code is executed. Figure 5-1 represents the communication flow. 101 Chapter 5: Connecting to and Using an Oracle Database Figure 5-1: Communi- cation flowchart. Client Workstation Oracle Net Port 1521Client Application - tnsnames.ora Database Instance - dev11g Listener Process - listener.ora Database Instance - db01 Database Server The client contains the client application and tnsnames.ora file. It communi- cates to the database server over Oracle Net on port 1521. On the database server a listener process is configured by way of the listener.ora file. The listener routes the incoming request to the target database instance (either dev11g or db01) and establishes the initial connection handshake between the database instance and client. Setting up tnsnames.ora You must provide the address or location of the database you’re trying to connect to. This information is often stored in the tnsnames.ora text file, which exists on the client you’re connecting from. Other methods of locating your database exist such as referencing an Oracle Internet Directory (OID), but tnsnames.ora is the most common method for clients. Note this “client” can be a user’s workstation; it can be a web application server, or even another database server. Here is a sample tnsnames.ora file: dev11g = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = classroom.perptech.local)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = dev11g) ) db01 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = classroom.perptech.local)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = db01) ) 102 Part II: Implementing Oracle on Your Own This particular tnsnames.ora contains 2 TNS (Transport Network Substrate) aliases, one for dev11g and one for db01. When connecting to a database instance, you actually specify the TNS alias (not database name). For exam- ple, sqlplus barb@dev11g uses dev11g as the alias. The TNS alias can be any name (such as dev11g or something more generic like dev or trainingdb); it doesn’t have to be the actual database name. That flexibility means you can have a generic alias and not hardcode the database name. Under HOST you specify either the DNS host name or the IP address of the server containing the database instance. Again, try to avoid hardcoded values such as IP address and use DNS names if possible. PORT is the port the server-side listener process is listening on. It’s also the port you connect across the network on for your Oracle Net traffic (thus the firewalls must be open on that port). SERVICE_NAME is the service name of the database instance you are attempt- ing to connect to. You can also use SID, although Oracle is promoting the use of SERVICE_NAME instead. The tnsnames.ora file is text based, and you can edit it by hand. After making changes, it’s not necessary to restart the database or listener process. Configuring the database listener with listener.ora The key file to the listener process is the listener.ora configuration file. This file identifies two things: ✓ Each database it will listen for ✓ On what ports (usually 1521 or 1526) The file is located in ORACLE_HOME/network/admin or under the Automatic Diagnostic Repository (ADR) infrastructure in ADR_BASE/diag/tnslsnr tree. Here’s a sample listener.ora file: # listener.ora Network Configuration File: /u01/app/oracle/product/11.1.0/db_1/ network/admin/lis tener.ora # Generated by Oracle configuration tools. SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (GLOBAL_DBNAME = db01) (ORACLE_HOME = /u01/app/oracle/product/11.1.0/db_1) 103 Chapter 5: Connecting to and Using an Oracle Database (SID_NAME = db01) ) (SID_DESC = (GLOBAL_DBNAME = dev11g) (ORACLE_HOME = /u01/app/oracle/product/11.1.0/db_1) (SID_NAME = dev11g) ) ) LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = classroom.perptech.local)(PORT = 1521)) ) (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521)) ) ) In the preceding code you see two main sections: SID_LIST_LISTENER and LISTENER. The SID_LIST_LISTENER section identifies each database instance that the listener will service connections for. It lists the global database name, ORACLE_HOME, and SID. As you need more databases, simply add the following section and then cus- tomize the relevant information: (SID_DESC = (GLOBAL_DBNAME = dev11g) (ORACLE_HOME = /u01/app/oracle/product/11.1.0/db_1) (SID_NAME = dev11g) ) The LISTENER section identifies what host the database exists on and what port it accepts connections on: (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = classroom.perptech.local)(PORT = 1521)) ) Here you see the listener will listen on the HOST (server) classroom. perptech.local and the port is 1521. Requests on other ports will not be acknowledged. You can add more databases, even if they’re different database versions to the listener.ora. If you have multiple database versions, run your listener with the highest version of the database software you have. You can also add additional LISTENER processes (if you want to listen on multiple ports, for example). 104 Part II: Implementing Oracle on Your Own You should be aware of one configuration option we don’t necessarily recom- mend: Shared Servers (also known as Multi-Threaded Servers — MTS). With this method, each user connection uses a shared process rather than a dedicated server process on the database server. In theory, having connections share a server-side process reduces memory use and is good for systems with lots of concurrent users. However, we’ve never seen it provide a noticeable benefit, and we wouldn’t consider it a common configuration. Note that this is different from connection pooling with application serv- ers, which is something we do recommend. What we outlined earlier, in the “Communication flow” section, is the dedicated server mode which is more common, provides better performance, and is required for DBA connections. The sqlnet.ora file is one additional configuration file. It can be client or server side, usually located with the listener.ora or tnsnames.ora file. The sqlnet.ora file is a special options file where you can add parameters to the Oracle Net architecture. This file can exist both on servers to impact the lis- tener process and on clients to influence TNS settings. For example, you can ✓ Add commands to force increased tracing, logging options, or encryption. ✓ Tell the listener to add a domain name to each database ✓ Direct the listener to look up connection information in an LDAP instead of a tnsnames.ora file. Here is a simple sqlnet.ora file: $ more sqlnet.ora NAMES.DIRECTORY_PATH=TNSNAMES The setting simply tells the client to use the tnsnames.ora file instead of any other resource (such as an LDAP). If you’re experiencing connection issues and your tnsnames.ora and listener. ora files look fine, don’t forget the sqlnet.ora. There may be a forgotten setting there causing issues. Starting and stopping the database listener The database listener process reads the listener.ora and sqlnet.ora files for its configuration; the DBA manages it using the lsnrctl command-line util- ity. You can use the utility to do these things to the listener: ✓ Start ✓ Stop 105 Chapter 5: Connecting to and Using an Oracle Database ✓ Check status There is no direct relationship between the listener process and the database itself; the processes operate independently. That means you can start the lis- tener before or after the database. But remember that the listener must be started before the database can ser- vice remote connections. To start the listener, issue the lsnrctl start command: $ lsnrctl start LSNRCTL for Linux: Version 11.1.0.6.0 - Production on 27-SEP-2008 03:04:48 Copyright (c) 1991, 2007, Oracle. All rights reserved. Starting /u01/app/oracle/product/11.1.0/db_1/bin/tnslsnr: please wait... TNSLSNR for Linux: Version 11.1.0.6.0 - Production System parameter file is /u01/app/oracle/product/11.1.0/db_1/network/admin/ listener.ora Log messages written to /u01/app/oracle/diag/tnslsnr/classroom/listener/alert/ log.xml Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=classroom.perptech. local)(PORT=1521))) Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521))) Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=classroom.perptech. local)(PORT=1521))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 11.1.0.6.0 - Production Start Date 27-SEP-2008 03:04:49 Uptime 0 days 0 hr. 0 min. 0 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/oracle/product/11.1.0/db_1/network/admin/ listener.ora Listener Log File /u01/app/oracle/diag/tnslsnr/classroom/listener/alert/ log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=classroom.perptech.local) (PORT=1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521))) Services Summary... Service “dev11g” has 1 instance(s). Instance “dev11g”, status UNKNOWN, has 1 handler(s) for this service... The command completed successfully $ 106 Part II: Implementing Oracle on Your Own If you need to stop the listener, you can issue the lsnrctl stop command : $ lsnrctl stop LSNRCTL for Linux: Version 11.1.0.6.0 - Production on 27-SEP-2008 03:04:19 Copyright (c) 1991, 2007, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=classroom.perptech. local)(PORT=1521))) The command completed successfully $ After changing the listener.ora file, you must restart the listener process. You can do this via the stop and start commands. An easier method is the lsnrctl reload command. It effectively restarts the listener process without the explicit stop and start. To determine what databases the listener is configured to service requests, you can read the listener.ora configuration file. Or, more easily, you can issue the lsrnctl status command: $ lsnrctl status LSNRCTL for Linux: Version 11.1.0.6.0 - Production on 27-SEP-2008 03:03:23 Copyright (c) 1991, 2007, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=classroom.perptech. local)(PORT=1521))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 11.1.0.6.0 - Production Start Date 17-SEP-2008 23:24:21 Uptime 9 days 3 hr. 39 min. 10 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/oracle/product/11.1.0/db_1/network/admin/ listener.ora Listener Log File /u01/app/oracle/diag/tnslsnr/classroom/listener/alert/ log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=classroom.perptech.local) (PORT=1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=classroom.perptech.local)(PORT=8080)) (Presentation=HTTP)(Session=RAW)) 107 Chapter 5: Connecting to and Using an Oracle Database Services Summary... Service “dev11g” has 2 instance(s). Instance “dev11g”, status UNKNOWN, has 1 handler(s) for this service... Instance “dev11g”, status READY, has 1 handler(s) for this service... Service “dev11gXDB” has 1 instance(s). Instance “dev11g”, status READY, has 1 handler(s) for this service... Service “dev11g_XPT” has 1 instance(s). Instance “dev11g”, status READY, has 1 handler(s) for this service... The command completed successfully $ This code shows listening for connections for the dev11g database. Logs for the listener process are stored in the listener.log file. Depending on database setup, the listener.log may be in one of these two spots: ✓ In ORACLE_HOME/network/admin ✓ Under the ADR infrastructure in ADR_BASE/diag/tnslsnr tree For more information on this file, see Chapter 12. Testing the connection The best way to test a connection is via the application, but that isn’t always possible. Preferably, you’re on the client tier and actually go through the same network path as the client applications. If you don’t do that, you may not be executing a valid test. To execute a connectivity test, follow these steps to determine whether you can connect to the database instance: 1. Go to the client tier. 2. See if Oracle client software such as SQL*Plus and tnsnames.ora is installed. 3. Execute a sqlplus username@tns_alias such as sqlplus barb@dev11g. 4. Enter the password to connect to the database. Using the tnsping utility is an even faster method that doesn’t require a password. This connects over the network via the listener and establishes a handshake. It then terminates the connection and reports the results, which you see here: 108 Part II: Implementing Oracle on Your Own $ tnsping dev11g TNS Ping Utility for Linux: Version 11.1.0.6.0 - Production on 18-SEP-2008 21:22:45 Copyright (c) 1997, 2007, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/11.1.0/db_1/network/admin/sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION_LIST = (DESCRIPTION= (ADDRESS_LIST= (ADDRESS= (PROTOCOL=tcp) (HOST= classroom.perptech.local) (PORT=1521))))) OK (20 msec) Testing connections is a good verification step for the DBA. If problems occur, it lets you catch them first instead of relying on users to report them later. Oracle Net Configuration Assistant It’s important to understand how the listener works and what different files control the communication process; that’s why we explain those parts first in this chapter. Many DBAs simply copy the same template files from one server to the next making only minor changes. However, Oracle does provide a GUI database assistant tool called Oracle Net Configuration Assistant to preconfigure tnsnames.ora and listener.ora for you on the server side. It can also be exe- cuted on the client side. It walks you through generating your configuration files and even tests the connection for you. We encourage you to test the Oracle Net Configuration Assistant and see if it’s easy for you, but we caution you to understand the files themselves. Through that understanding, you can better fix problems and gotchas. Sidestepping Connection Gotchas Setting up connections to an Oracle database doesn’t have to be difficult, but sometimes initial setup can be tough. Most of the time you, as the DBA, review the configuration and figure out the issue. In other cases, you need to work with the network people to trace connections or open firewalls. In still other cases, you work with the application experts and determine who the client application is attempting to connect to the database. 109 Chapter 5: Connecting to and Using an Oracle Database Many people fall into several gotchas: ✓ Remember to start the listener. This sounds obvious, but it’s not uncommon to start the database and forget to start the listener process. Scripting these steps helps eliminate these errors. ✓ Keep open the firewall on port 1521. It is common to have a firewall separating the database server from the users or web application serv- ers. That means Oracle Net traffic may be blocked; in fact, you should assume that you need to have the firewall opened on port 1521 until proven otherwise. Using the tnsping utility can help test these connections. ✓ Watch out for multiple tnsnames.ora files. On users’ workstations, multiple installations of Oracle client software are likely to have mul- tiple tnsnames.ora files. That becomes a problem when an update to tnsnames.ora is necessary, but not all the tnsnames.ora files are updated. This manifests itself in some applications working and others that don’t. Either have one common file or a script to update all the files. ✓ Copy and paste existing entries and change only the key parameters. Because tnsnames.ora is a text file, it invites people to edit it by hand. That is fine, but it’s easy to transpose a number (1512, for instance), mis- spell a server name, or insert an extra ) somewhere. Also, avoid using IP addresses for host information unless you really need to. Use the DNS server name instead and you won’t have to worry about the IP address changing without warning. None of these errors is insurmountable, but checking these items may save you some time. 110 Part II: Implementing Oracle on Your Own Chapter 6 Speaking the SQL Language In This Chapter ▶ Using SQL and the SQL*Plus Tool ▶ Getting help from SQL*Plus ▶ Using the Oracle data dictionary ▶ Seeing an overview of PL/SQL This chapter shows you some useful SQL and PL/SQL syntax and usage (that literally span over 1,000 pages that Oracle 11g has documented). With that understanding, we provide some helpful tricks by explaining and illustrating standard DBA commands and scripts that should be useful for everyday maintenance. We cover some SQL Developer examples too. And hey, you don’t want to be perceived as Microsoft SQL Server DBAs of the royal GUI echelon do you? I guess that depends on the pay. If you’re somewhat familiar with SQL or Oracle’s SQL*Plus, you might con- sider skimming through this chapter. If you find yourself feeling a little lost, consider ramping up on some SQL fundamentals first. Almost all good DBAs are proficient in SQL*Plus, Oracle’s SQL command- line executable. That is always the quickest and most efficient way to finding what you’re looking for. Several other tools help execute SQL commands. Those on the market include but aren’t limited to Toad, Embarcadero, SQL Worksheet, DB Console, and (my free favorite) Oracle’s SQL developer. Try to bear down and accept command-line interfaces before you get spoiled with what you might think is a simpler way. Using SQL in Oracle You might be asking what SQL is. Hopefully you know that it’s pronounced sequel and that it stands for Structured Query Language. 112 Part II: Implementing Oracle on Your Own SQL is an American National Standards Institute (ANSI) standard for com- municating with relational database systems. Database software like Oracle, MS SQL Server, DB2, MySQL, and others try to use the ANSI-compliant ver- sion of SQL. Today, you find many ANSI SQL-like versions but they all have their own tweaks. That’s where SQL*Plus comes in with Oracle. SQL*Plus is an ANSI-compliant SQL executable that has additional functional- ity for Oracle use like the following: ✓ Formatting ✓ Translating ✓ Calculating for reports or queries SQL*Plus is considered an interpreted language compiled on-the-fly like Java. Normally you install it with the Oracle database or client software. Its main uses include the following: ✓ Select data ✓ Insert ✓ Update data ✓ Delete data ✓ Create objects ✓ Drop objects ✓ Write procedural SQL (PL/SQL) Sharpening the SQL*Plus Tool First some definitions: ✓ A client is considered a user’s desktop PC used to do user stuff. The client interacts with the server. ✓ A server is considered a big-iron host that would contain the database software and the database files. The server processes requests with its massive muscle. Oracle software installed on a server can also be considered a client because like a client, Oracle’s tools can interact with many databases on the local server or on remote servers through the network; therefore, a command-line SQL*Plus client is usually available on both. 113 Chapter 6: Speaking the SQL Language Generally, you don’t want to install SQL*Plus clients on all user PCs. Having SQL*Plus or other Oracle tools on an end user’s PC is often considered a secu- rity or data integrity risk since that PC could be used to bypass the applica- tion’s built-in edit functionality and security. Users and applications normally only require the SQL*Net components, which allow client-side applications to communicate with the database. Modern applications and web servers have their own Oracle client installed on them and are web based, which would require a client-side Java runtime engine like Oracle’s J-Initiator or nothing at all. Chapters 4 and 5 cover environment variables and network configurations, respectively. If SQL*Plus does not work for you, then it’s not installed or simply not in your environment path. To troubleshoot this, start by reconnect- ing with Chapters 4 and 5. One final point: Oracle’s SQL*Plus has many faces (different looks and feel). For example, it can look a little different depending on your OS but the func- tionality is the same as long as the SQL*Plus versions are the same. MS DOS command-line SQL*Plus has some different OS functionality than the MS GUI SQL*Plus executable. Often you can’t find a SQL*Plus client version that matches the database release version. Keep that in mind when you jump into SQL*Plus, but don’t sweat it too much. That’s what testing is for. Using SQL Connection Commands To connect and execute SQL commands against the database, use SQL*Plus running on the client or the local host. Follow these steps to execute the SQL*Plus program from your PC or server: 1. Open a command prompt and type . 2. Enter your username and press Enter. 3. Enter your password and press Enter. The Oracle SID (also known as Host String or Connect Descriptor) can follow after the username with an @ and is optional. If the instance is running on your machine, then the environment variable ORACLE_SID determines which database you connect to if you don’t use a Host String. 114 Part II: Implementing Oracle on Your Own Here is an example of some connection types: [oracle@classroom ~]$ sqlplus SQL*Plus: Release 11.1.0.6.0 - Production on Sun Sep 7 11:40:06 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. Enter user-name: hr Enter password: Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> Here is an example of connecting to a remote database: Enter user-name: system@dev11g Enter password: Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> SQL*Plus Profile Scripts glogin.sql and login.sql SQL*Plus uses two profile scripts when you log in to Oracle using SQL*Plus. ✓ glogin.sql: This file resides in the $ORACLE_HOME/sqlplus/admin direc- tory. If it exists, it’s executed first when you log in. ✓ login.sql: This file can be found in many places but Oracle looks for it after glogin.sql based on your OS PATH variable, which usually begins in the present working directory (pwd). After that, it looks for it based on the SQLPATH operating system variable. Both are found and executed from the local environment you’re using (not the remote database software environment). Their purpose is to set SQL*Plus environment variables like the following: ✓ Line size ✓ Page size ✓ Text editor (notepad, vi, and so on) ✓ The SQL*Plus prompt It can also run SQL statements that tell you what database you just logged into. 115 Chapter 6: Speaking the SQL Language You can do several cool things with the glogin.sql and login.sql scripts. Here is an example of a login.sql script we use regularly: --define _editor=notepad *for Windows define _editor=vi column tablespace_name format a40 truncate column file_name format a45 truncate column username format a20 truncate set lines 132 set pages 55 set termout on set time on SET SQLPROMPT ‘&_USER@&_CONNECT_IDENTIFIER> ‘ select instance_name dbname, version from v$instance; There are operating system environment variables and SQL*Plus environment variables. For example, SQLPATH is an operating system variable and is set in the user profile on the OS. EDITOR is another OS-specific variable that you can set in the OS profile; or you can define another editor in the login.sql file with define _editor=vi. Use caution when updating the glogin.sql script on a shared server. Doing so affects every user’s SQL*Plus session if they’re not overriding it with a login. sql script. It’s an easy beginner’s mistake and it only shows peers that you’re a novice. SQL*Plus buffer and commands The SQL*Plus buffer is a session memory area that contains the most recent SQL statement or PL/SQL block and all SQL*Plus session environment set- tings. The most recent statements are in memory until the next statement is run or the session is terminated. It’s common practice to save the statements to a file if they’re large enough. Routinely, you will bounce from buffer ses- sion statements to files depending on the complexity of the statement. You can show the contents of the latest statements with the LIST command (or abbreviate it with L). You can also see all of the environment settings with the show all command. SQL*Plus commands Table 6-1 shows most of the commands and their abbreviations used to manipulate text within the SQL*Plus buffer. We recommend a hands-on approach to learning these commands. 116 Part II: Implementing Oracle on Your Own SQL*Plus buffer commands are not case sensitive. Table 6-1 SQL*Plus Commands and Abbreviations Command Abbreviation Usage APPEND text A text Adds text to end of the current line CHANGE/old/new c/old/new Changes old text to new text on current line CLEAR BUFFER CL BUFF Erases the buffer CONNECT user CONN user Connects as user DEL none Deletes the current line DEL n none Deletes the line number n DEL LAST none Deletes the last line EDIT ED Opens buffer into the default editor (vi/ notepad) EDIT filename ED filename Opens file with default editor GET filename none Loads filename into buffer; does not execute INPUT I Adds one or more lines after current line LIST L or ; Lists all lines in the buffer LIST n L n or n Lists line n SAVE filename SAV filename Saves buffer contents to file SET SET option Sets many available SQL*Plus options SPOOL SPO filename Saves output to a file on the operating system START STA, /, ; or @ Runs the current statement in the buffer START filename STA filename Loads file into buffer and executes QUIT or EXIT — Quits SQL*Plus You can abbreviate most SQL*Plus buffer and set commands to be more effi- cient. These abbreviations appear when possible in this section. Additionally, these commands are exclusive to Oracle’s SQL*Plus so some commands might not be available using third-party vendor products. 117 Chapter 6: Speaking the SQL Language The following listing shows some SQL*Plus commands. Notice the *, which denotes the current line. SYS@dev11g> select username from v$session where username is not null; USERNAME -------- DBSNMP HR ZEISC SYSMAN SYS SYSMAN DBSNMP SYSMAN SYSMAN SYSMAN 10 rows selected. SYS@dev11g> c/name/name, program 1* select username, program from v$session where username is not null SYS@dev11g> / USERNAME PROGRAM -------------------- ------------------------------------------------ HR MS ACCESS.EXE ZEISC SQL Developer SYSMAN OMS SYS sqlplus@classroom.perptech.local (TNS V1-V3) SYSMAN OMS SYSMAN OMS SYSMAN OMS SYSMAN OMS 8 rows selected. SYS@dev11g> l 1* select username, program from v$session where username is not null SYS@dev11g> i 2 and username = ‘SYS’ 3 / USERNAME PROGRAM -------------------- ------------------------------------------------ SYS sqlplus@classroom.perptech.local (TNS V1-V3) 1 row selected SYS@dev11g> 118 Part II: Implementing Oracle on Your Own Getting Help from SQL*Plus When you’re connected to SQL*Plus, you can get help from the SQL*Plus executable but help must be installed. Generally, you do that during database creation. To see if help is available, simply type help define while in a SQL*Plus. A large number of set commands available in SQL*Plus should be listed. If not, load information manually. The following steps and information guide you through the process: ✓ hlpbld.sql drops and create new help tables. ✓ helpdrop.sql drops existing help tables. ✓ helpus.sql populates the help tables with the help data. To load the command-line help, run the following help commands in an active SQL*Plus session. The following two examples use the help feature to explain the SQL*Plus DEFINE and COLUMN commands. 1. To install the help functionality, log in to SQL*Plus and type this: 2. Look at the help entry for the DEFINE command: You should see something like this: DEFINE ------ Specifies a substitution variable and assigns a CHAR value to it, or lists the value and variable type of a single variable or all variables. DEF[INE] [variable] | [variable = text] 3. Look at the help entry for the column command: You should see something like this: COLUMN ------ Specifies display attributes for a given column, such as: - text for the column heading - alignment for the column heading - format for NUMBER data - wrapping of column data 119 Chapter 6: Speaking the SQL Language Also lists the current display attributes for a single column or all columns. COL[UMN] [{column | expr} [option ...] ] where option represents one of the following clauses: ALI[AS] alias CLE[AR] …output snipped WRA[PPED] | WOR[D_WRAPPED] | TRU[NCATED] SQL language elements SQL has language elements that support the intention of the SQL statement. The following have implicit commits so there’s no use, ability, or reason to roll back or commit: ✓ Data Query Language (DQL) ✓ Data Control Language (DCL) ✓ Data Definition Language (DDL) You can use Transaction Control Language (TCL) in conjunction with DML. A commit or rollback is required if you change data within a table by inserting, deleting, or updating the data. By default, a commit is executed when you exit SQL*Plus properly with the EXIT or QUIT commands. Killing the SQL*Plus program or session automati- cally rolls back any DML that you haven’t committed. Be sure to commit transactions that you want to make permanent. Data Query Language (DQL) DQL is often used to select data from the database in the form of columns. At the least, it contains the key words SELECT and FROM with an optional WHERE, GROUP BY, and ORDER BY. select first_name, last_name, to_char(hire_date,’YYMMDD’) from hr.emp where substr(last_name,1,1) = ‘S’ order by first_name; 120 Part II: Implementing Oracle on Your Own Data Manipulation Language (DML) DML adds, updates, or deletes data. Its three key words are INSERT, UPDATE, and DELETE. update hr.emp set last_name = ‘Walsh’ where last_name=’Smith’ and first_name = ‘Lindsey’; Data Definition Language (DDL) DDL defines objects in a database. Its most used key words are CREATE, DROP, ALTER, and TRUNCATE. It creates, drops, or alters objects in the data- base like tables, views, or stored procedures. create table hr.certifications (employee_id number(6), cert_type varchar(30), date_completed date); truncate table hr.certifications; Data Control Language (DCL) Used to define privileges in a database to objects with key words like GRANT or REVOKE. revoke dba from hr; Or grant connect, resource to hr; Transaction Control Language (TCL) Used with DML, TCL defines transactional processing for record changes with the key words ROLLBACK, COMMIT, and SAVEPOINT. DQL, DCL, and DDL have implicit commits, therefore there is no use ability or reason to roll back or commit. You can use TCL with DML. If you change data within a table by inserting, deleting, or updating the data, then a commit or rollback is required. By default, a commit is executed when you exit from SQL*Plus properly with the EXIT or QUIT commands. Killing the SQL*Plus program or session auto- matically rolls back any DML that hasn’t been committed. Be sure to commit transactions that you want to make permanent. 121 Chapter 6: Speaking the SQL Language Using the Oracle Data Dictionary You don’t want to get into the thickness of SQL itself (only because there is another SQL For Dummies book for that). Check these regular DBA SQL state- ments that you can use to get familiar with Oracle’s Data Dictionary. The Oracle Data Dictionary is data about the data in the database (also known as metadata). Data dictionary views You might have access to four basic types of data dictionary views: DBA, USER, ALL, and V$. Each view is preceded by one of these key names: ✓ DBA_viewname: DBA dictionary views contains relevant information about the entire database. DBAs query these views to conduct mainte- nance research and are for DBAs only. A few examples are DBA_TABLES, DBA_USERS, DBA_TABLESPACES, DBA_DATA_FILES, DBA_FREE_SPACE, DBA_OBJECTS, and DBA_SEGMENTS. ✓ ALL_viewname: ALL dictionary views contains information accessible to the current user to which you’re connected. The view information avail- able is determined by the roles or privileges the user has been granted. A few examples are ALL_TABLES, ALL_OBJECTS, and ALL_SYNONYMS. ✓ USER_viewname: USER dictionary views only have information about the current user (schema) to which you’re connected. Examples are USER_TABLES, USER_OBJECTS, and USER_INDEXES. USER views are nor- mally used by developers that are creating applications under their own account. Because they have this information available, they don’t need DBA privileges. ✓ V$_viewname: These dynamic performance views read from the data- base control file and from memory. They contain information about how the database is currently operating. Typically they’re helpful for trou- bleshooting and performance tuning. Some examples are V$SESSION, V$LOCK, V$SGASTAT, and V$SQL. The Oracle database has many dictionary views so it’s easy to forget the exact name of the view you need to query. Use the following query to find these DBA views: 122 Part II: Implementing Oracle on Your Own Using desc As a DBA, it’s sometimes difficult to find what you’re looking for and to know what tables or views have the data you need. That’s why the describe com- mand is helpful. Use the following information to build simple queries that pull information from the data dictionary views. The following listing uses the describe command (desc) as a shortcut. The describe command summarizes database objects and their attributes. It’s useful for finding column names and data types of tables or views. SYS@dev11g> desc dba_users Name Null? Type ----------------------------- -------- -------------------- USERNAME NOT NULL VARCHAR2(30) USER_ID NOT NULL NUMBER PASSWORD VARCHAR2(30) ACCOUNT_STATUS NOT NULL VARCHAR2(32) LOCK_DATE DATE EXPIRY_DATE DATE DEFAULT_TABLESPACE NOT NULL VARCHAR2(30) TEMPORARY_TABLESPACE NOT NULL VARCHAR2(30) CREATED NOT NULL DATE PROFILE NOT NULL VARCHAR2(30) INITIAL_RSRC_CONSUMER_GROUP VARCHAR2(30) EXTERNAL_NAME VARCHAR2(4000) PASSWORD_VERSIONS VARCHAR2(8) EDITIONS_ENABLED VARCHAR2(1) SYS@dev11g> desc dba_role_privs Name Null? Type ----------------------------- -------- -------------------- GRANTEE VARCHAR2(30) GRANTED_ROLE NOT NULL VARCHAR2(30) ADMIN_OPTION VARCHAR2(3) DEFAULT_ROLE VARCHAR2(3) If you get an Oracle error like ORA-04043: object “DBA_USERS” does not exist when selecting from DBA views, then you don’t have DBA access or the role SELECT_CATALOG_ROLE. Also, it’s probably not a good idea to run DBA queries on a database at work; you could get into big trouble. You’re better off doing this at home on a test database. If the DBAs at work like you well enough, they might give you the role SELECT_CATALOG_ROLE for data dictionary access in a development or test database. It’s important to have a good understanding of the data dictionary view relationships. 123 Chapter 6: Speaking the SQL Language Using l Here is an example of selecting unlocked users from the dba_users data dictionary view. The l in this example is a shortcut for the command LIST, which lists the SQL in your session’s buffer. To get a list of UNLOCKED users, type this: 3. Determine whether this is the only file affected and whether it is a critical file. You also determine that it must be restored to a different disk. 4. Launch RMAN and take the data file offline: You see this: sql statement: alter database datafile 4 offline 5. Open the database: 6. Tell RMAN to restore to the correct location: 180 Part III: Caring For an Oracle Database In this case, it is disk u02, a different location. The output indicates that the file is being restored and recovered in the new location: executing command: SET NEWNAME Starting restore at 11-JUL-08 allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=131 device type=DISK channel ORA_DISK_1: starting datafile backup set restore channel ORA_DISK_1: specifying datafile(s) to restore from backup set channel ORA_DISK_1: restoring datafile 00004 to /u02/app/oracle/oradata/ dev11g/users01.dbf Starting recover at 11-JUL-08 using channel ORA_DISK_1 starting media recovery media recovery complete, elapsed time: 00:00:00 Finished recover at 11-JUL-08 7. When the recovery finishes, alter the tablespace back online: Quite a few more steps without the DRA, eh? Either way, it’s not too diffi- cult. If you haven’t already, make sure you set up a test database and practice these and other scenarios. You’ll be a recovery expert in no time at all. Incomplete recovery Incomplete recovery is usually a very unfortunate position to be in. Typically, it means you will be losing data (hence incomplete). Also, the DRA cannot help at all in this situation. In an incomplete recovery scenario, the database has not actually failed. Someone has done something to put the database in a state that requires you to go back in time. Here is a situation where incomplete recovery may apply: ✓ It is Monday morning. ✓ You have taken a backup of your database last night. ✓ You are in archive log mode. ✓ At 10:00 a.m., Tammy tells you she accidentally dropped a major table out of the accounting schema around 9:45 a.m. Not only did she drop it, she purged it from the recycle bin because she knew it was the right one. It wasn’t. ✓ Assuming you have no other way to retrieve the table from a logical backup or re-create it, you decide incomplete recovery is your only choice. 181 Chapter 8: Protecting Your Oracle Database ✓ You will take the database down to restore the backup from last night. Then you will roll the database forward to 9:44 a.m. and open it. ✓ Any transactions that occurred between 9:45 and 10:00 a.m. will be lost and have to be manually re-entered. A key piece of information is that Tammy told you she dropped the table at 9:45 a.m. Spend a few minutes doing some research to verify that the reported time is truthful. If you roll forward too far, the table will be dropped again during the recovery process and you will have to start over. Here are the steps to incomplete recovery: 1. Shut down the database. 2. Start up the database in mount mode. 3. Set the time for the restore to work off of. 4. Restore the database. 5. Recover the database. 6. Open the database with RESETLOGS. The control files will not match the data files. You have to re-sync the control files with the data files. 7. Open a prompt to your OS command line. 8. Log into your database with RMAN: 10. Use the following RMAN command to recover your database to the appropriate time (9:45 a.m. in this case): RMAN> run { set until time = “to_date(‘11-JUL-2008:09:45:00’,’DD-MON-YYYY:HH24:MI:SS’)”; restore database; recover database; sql “alter database open resetlogs”; } 182 Part III: Caring For an Oracle Database Once the command completes, you should see something like this: executing command: SET until clause using target database control file instead of recovery catalog Finished restore at 12-JUL-08 Starting recover at 12-JUL-08 using channel ORA_DISK_1 starting media recovery …output snipped… media recovery complete, elapsed time: 00:00:08 Finished recover at 12-JUL-08 sql statement: alter database open resetlogs 11. Make sure the table you were trying to recover has indeed been recovered. There’s nothing more embarrassing than telling everybody you fixed the problem only to have someone else discover that it still isn’t there. If you discover it is not there, do the recovery again, going back a little fur- ther in time. Recovering your database with copies Copies allow for superfast recovery and fewer technical recoveries when you have lost a disk and the file has to go to a different location. Some DBAs would argue a little that it’s incorrect to use the copy in the place you backed it up. Good DBAs subscribe to the mantra, Everything has its place; everything in its place. However, times are changing a little. For exam- ple, the popularity of large storage area networks (SAN), where all your files go to the same place, is growing. DBAs don’t have as much responsibility to orga- nize, separate, stripe and label data; nor do they have as much time. The SAN does all the protection and striping for you. Furthermore, Oracle has even released, in essence, its own volume manager: Automatic Storage Management (ASM). Relax your regimented file and naming conventions a little bit. Use that time to make better use of the features that Oracle that helps protect and manage data. You get a call from a user who is getting the following error: SQL> select * 2 from emp; from emp * ERROR at line 2: ORA-01116: error in opening database file 4 ORA-01110: data file 4: ‘/u02/app/oracle/oradata/dev11g/users01.dbf’ ORA-27041: unable to open file Linux-x86_64 Error: 2: No such file or directory Additional information: 3 183 Chapter 8: Protecting Your Oracle Database After some investigation, you see that someone has removed the data file from the USERS tablespace. This tablespace is critical and must be recovered immediately. You decide to recover with RMAN using a COPY of the data file. 1. Log into your target with RMAN. 2. Make sure you have a copy of your USERS tablespace data file: You should see something like this: List of Datafile Copies ======================= Key File S Completion Time Ckp SCN Ckp Time ------- ---- - --------------- ---------- --------------- 45 4 A 12-JUL-08 14878139 12-JUL-08 Name: /u01/app/oracle/flash_recovery_area/DEV11G/ datafile/o1_mf_users_47kn9j0z_.dbf Tag: FULL_DATABASE_COPY 3. Take the tablespace offline (since the database is open): < sql “alter tablespace users offline”;> You see this: sql statement: alter tablespace users offline 4. Switch to the copy: You see something like this: datafile 4 switched to datafile copy “/u01/app/oracle/flash_recovery_area/DEV11G/ datafile/o1_mf_users_47kn9j0z_.dbf” 5. Recover the copy, since it was taken earlier: < recover tablespace users;> You see something like this: Starting recover at 12-JUL-08 using channel ORA_DISK_1 starting media recovery media recovery complete, elapsed time: 00:00:04 Finished recover at 12-JUL-08 6. Alter the tablespace back online: < sql “alter tablespace users online”;> You see this: sql statement: alter tablespace users online 184 Part III: Caring For an Oracle Database All done! Do you see how quick that was without having to restore the file? Of course, you have to come to terms with it being in your flash recovery area. ✓ If that really bugs you, you can rename it and move it later, when you have a maintenance window. ✓ If that really bugs you, when you take the copy, you can copy it to an auxiliary area outside your flash recovery area (where you don’t mind it being) in case you have to use it. Chapter 9 Protecting Your Oracle Data In This Chapter ▶ Getting user authentication ▶ Exploring roles and privileges ▶ Employing VPD ▶ Auditing a database ▶ Encrypting the work Security is real concern. Especially in anything relating to computers and the Internet. As administrators of software applications like the Oracle database, we are concerned with security because we want to protect our data. Sometimes it’s because we don’t want people looking at our data. Another reason is to protect the data from being altered or corrupted. Being able to restrict and monitor the users in the system will help us provide a safe and secure operating environment for us and our customers or clients. Authentication Authentication is all about making sure your users are who they say they are. This process begins well before users even try to access the database. You need to set up a system that allows you to verify identity. You need a method for users to access the system that both identifies and restricts their privileges to their described needs. Finally, a security mechanism such as a password or operating system account is recommended so access isn’t open to anyone who tries. 186 Part III: Caring for an Oracle Database User authentication Once you set up your databases, the next step is to allow users access to the data. You may have all sorts of users in your environment, from people who need full access to the data and database (like a DBA) to an application that runs on a machine for users connecting from the Internet. User authentication, the first step to protecting your data, means verifying that a resource trying to connect to your database is authorized to do so. You can establish the following by authenticating users: ✓ Accountability: Having an accountability system forces users to take responsibility for their actions. It helps track down the culprits when problems occur. ✓ Trust: A system of authentication allows you to operate within a realm of trust. Make sure a potential user is qualified before they’re given data access. Qualifications can be as simple as a one-hour training class to a full-blown, government-sponsored background investigation. ✓ Proper privileges: You must restrict and grant access according to a resource’s identity and qualifications. Different resources have different type of access to accomplish different jobs. This capability is in place through a system of varying roles and privileges. ✓ Tracking mechanisms: Many databases need a Big Brother. When some- thing goes wrong, a tracking mechanism can help you hunt down and plug any security holes. It can also help you make sure resources in your environment aren’t snooping. Security past In the past, Oracle has given us tools to imple- ment very secure password authentication methods, but they have left the implementation up to us almost entirely. With each release of the database, Oracle has increased default security in the system. Oracle has been non- secure in the past. However, administrators had to deal with access being nearly wide open when software was installed and a database was created. DBAs had to set and manage authentication. Unfortunately, not all database users knew what to configure and lock down. Many internal accounts were created with high levels of access with default passwords that were easily found anywhere on the Internet. 187 Chapter 9: Protecting Your Oracle Data Password authentication Password protection is the most common way to protect data in computer systems. This applies to bank ATMs, Internet web sites, and of course, your Oracle database. Password protection helps establish identity. Passing this verification is the first step in showing you’re a trusted member of the club. Nowadays when you create the database ✓ Default accounts are locked. ✓ SYS and SYSTEM passwords are chosen and set during database creation. ✓ Password security is enhanced by forcing complex passwords. With these measures, the database is fairly secure as soon as it’s created. Chapter 5 covers user creation; this chapter expands on password security options. Enforcing password security with profiles A password profile is a mechanism in the database that forces a user to follow guidelines when creating or changing passwords. The guidelines help pro- vide stronger security in the system by not allowing weak passwords. Are you guilty of the following? ✓ Making password the same as the username ✓ Making password your password ✓ Reusing the same password when the system asks you to change Having to remember complex passwords is sometimes inconvenient, but accept it as part of your responsibility. If nothing else, how would you like to be blamed for someone guessing your password? Nevertheless, password profiles are a DBA tool and they let you do the following: ✓ Limit the number of times a password can be reused. If you want to give your users a break, let them reuse the password twice — but that’s it. ✓ Limit the amount of time before a password can be reused. Maybe you let them reuse the password, but they have to wait 90 days to do so. ✓ Limit failed login attempts. If this number is met, you can lock the account until a security administrator unlocks it or for a certain period of time. 188 Part III: Caring for an Oracle Database ✓ Password lock time. If a password is incorrectly entered the number of times based on the failed login attempts setting, you can force a waiting period before a user can try again. This can help against brute force attacks, where a machine bombards your database with a password cracker. ✓ Give passwords a life time. Once this threshold is met, ask the user to change his password. ✓ Have a password grace time. Once the life time is reached, the user is prompted with “You have X number of days to change your password.” ✓ Check password complexity. A verification function • Makes sure the password and username are different • Makes sure the new password differs from the previous by three characters • Ensures the password is made up of alphabetical, numeric, and special characters. You can create your own password verify function and attach it to a profile. A password verify function is a program written in PL/SQL that examines pass- words when they’re chosen and accepts or rejects them based on criteria. If you have special password requirements, you can write your own password verify function and assign it to your password profile using the PASSWORD_ VERIFY_FUNCTION attribute of the profile. Oracle supplies a standard password verify function with the database. By default, it ensures the following: ✓ Password is not the same as the username (forward and backward) ✓ Password is more than seven characters ✓ Password is not the same as the server name ✓ Password is not a common poor choice such as welcome1, password, database, abcdefg To use Oracle’s provided password verify function, follow these steps: 1. Log into SQL*Plus as SYS 2. Run the following: $ORACLE_HOME/rdbms/admin/utlpwdmg.sql This creates the default password verify function and assigns it to the DEFAULT profile. If you’re comfortable with PL/SQL, you can even take Oracle’s example file and modify it to fit your needs. 189 Chapter 9: Protecting Your Oracle Data Creating a password profile To create a password profile follow these steps: 1. Log into the database via SQL*Plus as SYSTEM. 2. Create the profile and limit the following: failed login attempts, pass- word lock time, and password life time: In this example failed login attempts are limited to three, password lock time is limited to 15 minutes, and password life time is limited to 90 days. You see this: Profile created. The password lock time in the preceding code is 1/96. In Oracle time, that is 15 minutes. You see, the whole number 1 is 1 day, and 1/24 is one hour. Divide 1/24 by 4 and you get 1/96 (or 15 minutes). 3. Assign the report writer user profile to a user: This example assigns the new profile to the HR user. You see this in return: User altered. DEFAULT profile What if you don’t give your users a profile? In that case, all users have the DEFAULT profile. By default in Oracle 11g, the DEFAULT profile limits the following: ✓ FAILED_LOGIN_ATTEMPT = 10 ✓ PASSWORD_GRACE_TIME 7 (DAYS) ✓ PASSWORD_LIFE_TIME 180 (DAYS) ✓ PASSWORD_LOCK_TIME 1 (DAY) ✓ PASSWORD_REUSE_MAX UNLIMITED ✓ PASSWORD_REUSE_TIME UNLIMITED 190 Part III: Caring for an Oracle Database You can edit your profile or the DEFAULT profile. For example, to change the failed login attempts setting to 3 on the DEFAULT profile, type the following: You see this: Profile altered. Operating system authentication You may not always want to require a user password. In those cases operating system authentication can be useful and, if set up properly, offer some secu- rity advantage over using a password. Use operating system authentication with caution though. Operating system authentication recognizes a user as logged into the OS and waives the password requirement. Operating system authentication can be especially useful when you have an application that requires a log in to the database to run a program. Say a job runs every night to generate reports and deposit them into a directory. How will the user inside your batch job connect ? You could embed a pass- word in the program, but that is not secure. Instead, you create an account in the database that links to the OS user and configure it with OS authentica- tion. That way, you protect the OS user’s password, and avoid a traditional username/password combination for the user to log in to run the reports. You’re safe as long as only authorized personnel know the OS user password. Type this code to create an OS-authenticated user in Oracle for someone named REPORTS: You see this: User created. Notice how the OS user is called REPORTS and the Oracle user is called OPS$REPORTS. 191 Chapter 9: Protecting Your Oracle Data The user prefix OPS$ must precede the OS username for the username to be identified externally. External identification means that instead of the user requiring a password in the database, Oracle looks to the OS and matches the username (minus the OPS$) to a user on the operating system. Oracle assumes that since the user is logged into the OS, it must be authenticated. You can change that prefix, OPS$, by revising the Oracle parameter OS_AUTHEN_PREFIX. After setting up all the necessary privileges for that user (detailed later in this chapter), the user can log in from the OS command line without a password: Granting the Privileged Few Once you create a user, you have to decide what types of things the user can do in the database. This includes the following: ✓ Logging in ✓ What data they can access ✓ Starting and stopping the database ✓ Whether they can create tables, indexes, and views ✓ Delete data ✓ Do backups Decide what a user can do via privileges. The database has two types of privileges: ✓ System privileges control what a user can do in the database. For exam- ple, can they create tables, create users, drop tablespaces? These privi- leges apply mainly to adding or changing structures in the database. ✓ Object privileges control how a user can access the actual data in the database. For example, what data can they see, change, or delete? These privileges apply primarily to rows in a table or view. Manage all privileges with the GRANT and REVOKE commands. It’s pretty clear which one gives, and which one taketh away. However, you form the commands depending on the type of privilege. 192 Part III: Caring for an Oracle Database System privileges System privileges are the first privileges any user needs. There are literally hundreds of system privileges. This chapter lists the common ones that include about 90 percent of what users will need. The CREATE SESSION privilege gives users access to the database. Follow these steps to grant CREATE SESSION privileges to the OPS$REPORTS user: 1. Log in to the database as the user SYSTEM. 2. Type the following: You see the following, which means OPS$REPORTS can connect to the database: Grant succeeded. What if the password for the OS user REPORTS has been compromised? A quick way to make sure that user can no longer access the database, exter- nally or not, is to revoke the CREATE SESSION privilege from that user. Revoke the CREATE SESSION from OPS$REPORTS with these steps: 1. Log in to the database as SYSTEM. 2. Type the following: You see this: Revoke succeeded. When that user tries to connect he sees this: ERROR: ORA-01045: user OPS$REPORTS lacks CREATE SESSION privilege; logon denied 3. Address the security breach. 4. Re-grant the privilege. Processing will continue as normal. 193 Chapter 9: Protecting Your Oracle Data A user might also have these system privileges that allow them to create objects in the database: ✓ RESUMABLE allows jobs to be suspended and resumed when space restrictions are met. ✓ FLASHBACK ARCHIVE allows users to retrieve data from the past. See Chapter 14 for more about flashback archiving. ✓ CREATE JOB allows users to create jobs that can be run in the Oracle Scheduler. ✓ CREATE SYNONYM allows users to be able to create alias for objects for easier access. These apply commonly to developers: ✓ CREATE TABLE ✓ CREATE VIEW ✓ CREATE SEQUENCE ✓ CREATE PROCEDURE ✓ CREATE TRIGGER DBAs commonly have these privileges: ✓ CREATE ANY TABLE creates tables in any user’s schema. ✓ DROP ANY TABLE drops tables from any user’s schema. ✓ CREATE TABLESPACE creates tablespace storage areas. ✓ ALTER USER changes user characteristics. ✓ DROP USER . . . uh, drops a user. ✓ ALTER SYSTEM changes system operation parameters. ✓ GRANT ANY OBJECT allows grantee to manage any object privilege against any object in the database. Very powerful! WITH ADMIN OPTION is another feature with system privileges. You can grant this system privilege as part of a system privilege to allow the user to grant the privilege to someone else. For example, say you’ve hired a new DBA with the username RPLEW. You want RPLEW to connect to the database with the CREATE SESSION privilege, but you also want him to be able to grant that privilege to someone else. 194 Part III: Caring for an Oracle Database To grant a system privilege WITH ADMIN OPTION 1. Log into SQL*Plus as SYSTEM. 2. Type the following: You see this: Grant succeeded. Now RPLEW can administer CREATE SESSION as well. If WITH ADMIN OPTION is revoked, all users given that privilege by that person will retain the privileges. Act accordingly. Object privileges Object privileges control data access and modification. Understanding object privileges You can grant only eight object privileges: ✓ SELECT lets the recipient select rows from tables. More on tables in Chapter 7. ✓ INSERT lets the recipient insert rows into tables. ✓ UPDATE lets the recipient change existing rows in tables. ✓ DELETE lets the recipient remove existing rows from tables. ✓ REFERENCES lets a user create a view on, or a foreign key to, another user’s table. More on foreign keys in Chapter 7. ✓ INDEX lets one user create an index on another user’s table. More on indexes in Chapter 7. ✓ ALTER lets one user change or add to the structure of another user’s table. ✓ EXECUTE lets the recipient run procedures owned by another user. Keep these privilege tidbits in mind: ✓ When you own an object, you automatically have all the privileges on that object. In other words, you don’t have to be granted SELECT on your own table. ✓ Object privileges cannot be revoked from the owner of an object. 195 Chapter 9: Protecting Your Oracle Data ✓ Whatever schema owns the object ultimately controls that object’s privileges. ✓ Without express permission, no one else can manage the object privi- leges of said object — well, no one except a user who might have the system privilege GRANT ANY OBJECT (usually reserved for DBAs). ✓ Object privilege cannot be revoked by anyone but the person who granted it except for someone with the GRANT ANY OBJECT privilege. Not even the owner can revoke a privilege on her own object unless she was the grantor. Granting object privileges In the following steps, the users MAGGIE, JASON, and MATT work in a data- base that contains recipes. This example uses object privileges to allow them to view and add more recipes. 1. Log in. 2. Type the following: This lets user MAGGIE allow JASON to select from her VEGETARIAN_ RECIPES table. She sees this: Grant succeeded. Similar to WITH ADMIN OPTION of system privileges, object privileges have something called WITH GRANT OPTION. ✓ MAGGIE can allow JASON to be able to INSERT into her table and allow JASON to pass on that privilege: ✓ JASON can pass on that INSERT privilege to MATT: ✓ MAGGIE cannot revoke the INSERT privilege from MATT. She has to ask JASON to do so. ✓ If JASON refuses to revoke INSERT privileges for MATT, MAGGIE can revoke the privilege from JASON and, in turn, revoke it from MATT. It’s called a cascading revoke. Note that this is different from system privileges. ✓ MAGGIE can revoke the INSERT privilege from JASON and in the mean- time automatically revoke them from MATT: She sees this: Revoke succeeded. 196 Part III: Caring for an Oracle Database If a user wants to see what object privilege they have given out, they can query the view USER_TAB_PRIVS. For example, MAGGIE can see what privileges JASON has left on her objects: You see something like this: USER_NAME AUDIT_OPTION SUCCESS FAILURE ---------- --------------------------- ---------- ---------- SYSTEM AUDIT BY ACCESS BY ACCESS CREATE SESSION BY ACCESS BY ACCESS CREATE USER BY ACCESS BY ACCESS ALTER USER BY ACCESS BY ACCESS DROP USER BY ACCESS BY ACCESS ROLE BY ACCESS BY ACCESS HR CREATE TABLE BY ACCESS BY ACCESS HR CREATE ANY TABLE BY ACCESS BY ACCESS You can interpret the output this way: ✓ USER_NAME tells you whether this privilege is being monitored for everyone or specific users. Columns without a username mean the privilege is being audited for everyone. 206 Part III: Caring for an Oracle Database ✓ AUDIT_OPTION is the privilege being audited. ✓ SUCCESS is whether the privilege is for success. ✓ FAILURE is whether the privilege is for failure. Even if the view says BY ACCESS, you can’t audit a system privilege by session. To see the audits for objects, query the DBA_OBJ_AUDIT_OPTS view. For example, view the audits turned on for objects owned by HR for the SELECT, INSERT, UPDATE, and DELETE privileges: You might see something like this: OS_USERNAM USERNAME OWNER OBJ_NAME ACTION_NAME ---------- ---------- ----- -------------------- --------------- oracle OE HR DEPARTMENTS SELECT oracle OE HR DEPARTMENTS INSERT Again, specific columns are selected. There is so much information in this table, that there is no way to fit it into this chapter. This output shows that the OE user selected from departments and inserted into departments. Try your own queries to see what kind of information you can get. Turning off audits Turning off auditing is as easy at turning it on. You may have to use the audit options to help remember what you have turned on. Once you identify the audits you no longer need, use the NOAUDIT command to turn off the audits. 208 Part III: Caring for an Oracle Database Say you are auditing all selects in the entire database and decide this is way too much information. Turn off this audit: You see this: Noaudit succeeded. When you turn off an audit, you have to be very specific to reverse the exact syntax of the original audit command. For instance, NOAUDIT SELECT TABLE noaudit select table won’t turn off an audit that was defined as AUDIT SELECT TABLE BY OE. The difference is “BY OE”. You would have to say NOAUDIT SELECT TABLE BY OE. Type this to turn off audits on alter system: You see this: Noaudit succeeded. If you want to turn off auditing for the table HR.DEPARTMENTS for SELECT by ACCESS, type this: You see this: Noaudit succeeded. Encrypting a Database Just because someone can’t get into your database doesn’t mean she doesn’t have access to your data. A clever hacker who gains access to your Oracle database’s raw files can extract plain text data from these files. Raw files include the following: ✓ Data files (see Chapter 2) ✓ Recovery Manager backup files (see Chapter 8) ✓ Data Pump export files (see Chapter 10) 209 Chapter 9: Protecting Your Oracle Data Using Oracle’s Advanced Security Option can help scramble, or encrypt, the data in these files so someone who gets ahold of them can’t extract the data. As of this writing, the Advanced Security Option in the database is a sepa- rately licensed feature. Encrypt these file by using Oracle Wallet and an Encryption Key. Depending on the strength of an encryption key, you can make these files virtually inde- cipherable to anyone. We are not discouraging anyone from using encryption, but it comes at a cost: ✓ There is most certainly CPU overhead to view or work with encrypted files. Depending on the encryption strength, this can be significant. ✓ There is a fair amount of management overhead involved in an environ- ment that requires encryption. You have to maintain proper access to Oracle Wallets and passwords. You typically have to have a dedicated authority to pass out the encryption keys and password access. There are also expirations on many of these items and encrypted data must be man- aged in a way that an expired key won’t invalidate access to your data. Some would argue that data security is priceless. However, not all real-world data needs security at the highest of levels. Sometimes your database might house strictly public information. You might want to restrict access to it with usernames, passwords, and privileges to prevent tampering or destruction; that may be enough. 210 Part III: Caring for an Oracle Database Chapter 10 Keeping the Database Running In This Chapter ▶ Performing daily common tasks ▶ Automating Jobs via the Database Scheduler ▶ Using Oracle Data Pump In most instances, managing an Oracle database is a full-time job. That’s why some people have the job title Oracle database administrator (DBA). A DBA must keep on top of a plethora of activities to make sure your data- base runs smoothly and doesn’t let you down when you most need it. The 11g Oracle database needs less attention in areas that were traditionally very hands-on. However, each release has new features that require the coddling and care that older features no longer need. Besides basic care and feeding, you might be asked to do some things on a regular basis: for exam- ple, loading data or scheduling jobs. In this chapter we investigate some of the daily maintenance tasks you will find yourself doing, how to use the Oracle scheduler, and load and unload data using Oracle Data Pump. Doing Your Chores This section identifies some of the common actives you as DBA might per- form. All databases are different. Each DBA has unique tasks and common management responsibilities. You might discover that not all the common tasks in this section apply to you. However, we think most of them do. On the other hand, you might do something every day that’s unique to your environment (and maybe everyone else’s too). We apologize for that, but think this chapter’s guidelines get you started toward a well-maintained, reliable database. 212 Part III: Caring for an Oracle Database Making way, checking space A lot of areas in the database require you to check on space for growth and shrinkage. Most people need to watch out for growth. In our experience, most databases grow over time — not shrink. Some environments are severely restricted regarding how much space is available. In that case, identifying database resources that allow you to reclaim space can be equally valuable. Lastly, not having extraneous, empty blocks of storage in the database can also help performance. Chapter 7 explains that when you create a brand-new tablespace, you choose a file for that tablespace to store its data. A tablespace is just a logical pointer to a file or files on the operating system. The file is the physical component of storage in Oracle. Everything is ultimately stored in a file. Say you create a tablespace called MY_DATA by typing this: When this tablespace is created, Oracle allocates 10MB of space from the operating system. The OS sees this space as used. However, if you look in the database, this space is free. Essentially the space “disappears” from the OS and “appears” in the database. Again, when you create a tablespace, the system administrator sees that the space on the system has shrunk; to the DBA, the database has grown. We’re beating this to death because this distinction is important. Imagine that you have 100GB of space available on the OS and you create a 99GB tablespace. Someone looking on the OS side would start sounding alarms: New space must be purchased! But the DBA can calm any fears by saying, “Don’t worry. That 99GB is still free, but Oracle owns it now. The OS can’t see it.” Before you jump into adding space, how much space is actually unused in your database? Too often people add space to a system that has plenty of free space available. You can monitor available real estate in a tablespace a couple different ways: ✓ Use Enterprise Manager database control. ✓ Query the data dictionary. 213 Chapter 10: Keeping the Database Running Since not everyone has the Enterprise Manager tool, we show you both ways. Enterprise Manager Enterprise Manager offers a couple ways to check space depending on what you want to see. 1. Log into Enterprise Manager as a DBA user. 2. Go to the home page. 3. Click the Server tab. 4. Click the Tablespaces link in the Storage section. You see a screen like Figure 10-1. Figure 10-1: Tablespace usage screen in Enterprise Manager looks like this. If you look closely a lot of information is available here: ✓ Tablespace Name: By row, which tablespace contains information/data. ✓ Allocated Size (MB): The amount of space that the tablespace currently has access to on the file system. It doesn’t mean that much space is unused. It’s the total amount of used and free space in megabytes (MB). ✓ Space Used (MB): The amount of space, in megabytes, you’ve used creating objects and inserting/loading data. 214 Part III: Caring for an Oracle Database ✓ Allocated Space Used (%): A graphical representation of how much space is used. Nice for reports and showing to people who prefer pictures. ✓ Allocated Free Space (MB): The amount of space, in megabytes, left for creating objects and loading data. ✓ Data files: How many data files are part of the tablespace. If you have more than one data file, click the Tablespace Name link to see all of them. SQL If Enterprise Manager isn’t available in your environment, a couple of SQL queries can get you the same information. 1. Log into SQL*Plus. 2. Type the following code: < select tablespace_name, file_name, bytes from dba_data_files;> With this code you get the tablespace name, its associated data files, and their sizes. You see something like this: TABLESPACE_NAME BYTES --------------- -------------- UNDOTBS1 267,386,880 SYSAUX 1,200,553,984 USERS 101,777,408 SYSTEM 891,289,600 EXAMPLE 104,857,600 MY_DATA 10,485,760 The query sums the bytes and groups by tablespace_name in case the tablespaces have more than one data file. 3. Type this to get the free space available: < select tablespace_name, sum(bytes) bytes from dba_free_space group by tablespace_name;> You see something like this: TABLESPACE_NAME BYTES --------------- -------------- SYSAUX 264,503,296 UNDOTBS1 255,524,864 USERS 33,226,752 SYSTEM 6,422,528 EXAMPLE 23,724,032 MY_DATA 10,420,224 This represents what’s left over in your tablespaces that you can use for creating objects and loading data. 215 Chapter 10: Keeping the Database Running 4. Take those numbers and calculate your percentages. If you’re clever with SQL, you can do it all in one query. You can see where Enterprise Manager makes things very easy here. We’d love to say it’s as simple as that. Alas, more goes into it whether you use Enterprise Manager or SQL. You see, the preceding sets of steps give you a rough estimate. It’s a pretty good estimate, but it’s not exact. Will it get you through the night knowing you have enough space for batch jobs to run? Yes, probably. Beware the false numbers caused by ✓ When you create a tablespace, the space is taken away so the OS can’t see it. Similar things can happen within the database. For example, when you create table, by default it creates an extent 64k big. That 64k is reserved for rows so it no longer shows up in your free space allocation table. What if you took a 10MB tablespace and created 150 new tables with 64k initial extents? No data, just empty tables. Your free space view would tell you that only 0.1MB of that 10MB is left, yet you haven’t put any data into the table. Enterprise Manager would tell you the same thing. Later in the chapter we talk about how you can see how much space is used within a table for more accurate space readings. ✓ Autoextensible data files (described in Chapter 7). A data file might say it’s 10MB, but if it reaches that, it automatically grows up to the maxi- mum size specified in the autoextend clause. For a query that shows your tablespace sizes more accurately, type this: < select tablespace_name, file_name, bytes, autoextensible, maxbytes from dba_data_files;> You see something like this: TABLESPACE_NAME BYTES AUT MAXBYTES --------------- -------------- --- --------------- USERS 101,777,408 YES 34,359,721,984 UNDOTBS1 267,386,880 YES 34,359,721,984 SYSAUX 1,200,553,984 YES 34,359,721,984 SYSTEM 891,289,600 YES 34,359,721,984 EXAMPLE 104,857,600 YES 34,359,721,984 MY_DATA 10,485,760 NO 0 In this example, the AUT column stands for autoextensible. If it shows YES, the MAXBYTES column tells you how big the data file can automatically grow. This detail is important when you’re deciding whether to add space. 216 Part III: Caring for an Oracle Database If you look back at Figure 10-1 and compare it to the output of the preceding query, you see that Enterprise Manager doesn’t take a data file’s autoextensi- bility size into account. Follow these steps to see the information in Enterprise Manager: 1. Go to the Tablespaces page. 2. Choose Datafile from the Object Type drop-down menu. The screen lists data files instead of tablespaces. 3. Click the radio button next to the data file to want to learn more about. 4. Click the View button above the data file listing. You see more details, including autoextensible and maximum file size. Monitoring space in your segments Segments are objects that take up space in the database. Segments are objects that, when created, allocated one or more extents from the free space in your tablespaces. The two most common databases segments follow: ✓ Tables ✓ Indexes Before putting in any data in a table, Oracle goes to the tablespace where it lives and allocates an extent. You can call this a used extent because it belongs to an object. The remaining space in the tablespace is free extents you can use when objects grow or new objects are created. As you start putting data into that table, the extent that was allocated upon creation begins to fill up. Once it reaches capacity, the table goes out to the tablespace and grabs another extent. It continues until either you stop adding data or the tablespace runs out of free space. To have a better idea of how objects grow, consider these guidelines: ✓ When you first create an object, the default extent size is 64k. ✓ The object continues to grow on 64k extents until it has 16 extents. ✓ The 17th extent is 1MB. ✓ It continues to grow in 1MB extents for the next 63 extents (total of 64, including the first 1MB extent). ✓ The 81st extent is 8MB. ✓ After 8MB extents, the last size Oracle uses is 64MB extents. 217 Chapter 10: Keeping the Database Running Knowing how your segments grow can help you predict space requirements. This is an important skill to have when monitoring storage. If you constantly insert data into your table, you got it covered. However, that isn’t always the case. Some tables grow and shrink. To be specific, they grow, but the shrinking, if necessary, is up to you. First of all, it comes in handy to understand how the objects in your applica- tion are used. Consider these examples: ✓ What tables grow? ✓ What tables, if any, shrink over time? ✓ What tables receive inserts and are never added to again except for reads? ✓ What tables are under constant manipulation (INSERT, UPDATE, DELETE)? Tables that stay the same are easy. You don’t have to worry much about those unless you want to tune them for performance. We already covered how to monitor a table’s growth, so any tables that grow without getting any rows deleted are covered…unless, again, you want to tune them for perfor- mance (but that’s another topic). The tough ones ✓ Tables that shrink and grow ✓ Tables that only shrink Growing and shrinking: Tricky tables A table that fits this category might be loaded every night, then deleted from throughout the day, like a batch processing table — for example, an ORDERS table that’s batch loaded at night from all the orders that were taken from a web site; as the orders are processed the next day, rows are deleted one by one. At the end of the day, all the rows are gone. What do you need to moni- tor for this table? You should be most concerned with how big the table gets each day after the batch load. Businesses want orders to increase. What about the deletes? Should you shrink the table at the end of the day before the next batch load to free up space? Absolutely not. Although it’s small, the growth of an object is overhead on the system processing. By leaving it the same size day to day, you know the space will be constantly reused. It’s kind of like recycling. You mainly want to monitor this type of object for growth. 218 Part III: Caring for an Oracle Database What about a table that gets mostly inserted into, but also gets deletes? Say for every 1 million rows inserted in a week, 30 percent are deleted. This table can present an interesting challenge. Take a quick look at how rows are inserted to better understand how objects grow and use space: ✓ You have a new table with one 64k extent. ✓ Your block size is 4k so that extent is 16 blocks. ✓ You start inserting data; 100 rows fit in a block. ✓ By default Oracle fills blocks 90 percent full and then stops (so you can update the row later and have it grow). For example, some fields are left null until a later date, then you fill them in. You don’t want the block to get filled too easily by an update; otherwise Oracle has to move the row to a new block that fits it. This rows migration degrades performance. ✓ When all the blocks are filled in the free extents, the table allocates a new extent and the process starts over. What if you start deleting rows at the same time you’re inserting? Will Oracle reuse the space where you deleted the row? It depends. Again, Oracle has a built-in feature that sacrifices space in favor of performance. Oracle inserts a row into a block that was once full, but only if deletes bring the block to 40 percent full. Oracle doesn’t want to manage a block that teeters between full, not full, full, not full, and so on. Although Oracle has reduced the performance overhead that comes with managing blocks and which ones you can insert into, manag- ing block storage still has a cost associated with it. Imagine you have a table with 10,000 blocks and are constantly inserting and deleting from that table. Oracle could spend all the CPU cycles managing what blocks can have inserts and which can’t if there were only a one-row difference between full and not- full blocks. That’s why Oracle uses the 40-percent rule. A block takes all the inserts it can until it’s 90 percent full, but the block can’t get back in line until it’s been reduced to 40 percent full. Again, what if you insert 1 million rows a week and delete 30 percent of them? What if the 30 percent that you delete are randomly selected and spread evenly across the blocks? Over time, those blocks never get down to 40 per- cent full. After a year, you may have a table that is 10GB with 3GB of it empty row space that won’t be reused. 219 Chapter 10: Keeping the Database Running As with many other operations, you have a couple of ways to determine whether you can release an object’s space. You must do that after evaluating the object’s usage pattern. Apply the following methods only to objects whose space you feel isn’t getting reused. Else, you waste your time and untold CPU and IO resources. ✓ Enterprise Manager ✓ Math Enterprise Manager Enterprise Manager is the easy way. A built-in tool called the Segment Advisor goes to the segment blocks and determines if an unused row space can be de-allocated. It’s relatively easy to use. 1. Log into Enterprise Manager as a DBA user. 2. From the home page, scroll to the bottom to the Related Links section. The three columns are shown in Figure 10-2. 3. Click the Advisor Central link in the middle column. At the top of the next page, you see three more columns of links. Figure 10-2: Related Links section of Enterprise Manager home page. 4. Click Segment Advisor. Figure 10-3 shows the Segment Advisor: Scope page. You can config- ure the segment advisor to run against tablespaces or specific schema objects. It points out that the database automatically determines what objects are work candidates. If your objects aren’t new to the system (the automatic job runs daily), see if they’re already identified. 5. Choose the Schema Objects radio button and click Next to check a specific object. Next you have to add the object or objects you want to analyze. 220 Part III: Caring for an Oracle Database Figure 10-3: The Segment Advisor: Scope page lets you choose between analyzing segments or tablespaces. 6. Click the Add button. The segment search screen appears. 7. Enter your information. Figure 10-4 shows a search for objects named like emp in the schema hr of type Table. Figure 10-4: Use the segment search screen to select objects for analysis. 8. Click Search, select your object by checking the box, and click OK. 9. When finished adding objects, click Next. 10. Indicate when you want to run the analysis. On a large object that’s gigabytes in size, consider doing this off-hours or over the weekend; it can strain the system. 221 Chapter 10: Keeping the Database Running 11. Click Next. The final screen reviews your job. 12. When you’re satisfied, click Submit. We chose a relatively small table call emp, which is engineered to rec- ommend space shrinkage. Once your job runs, you can click the link identified by your job name to get results and recommendations by tablespace. 13. Click the Recommendation Details button. Figure 10-5 shows the EMP table is recommended for space reclamation. Figure 10-5: You can reduce the EMP table by 11MB. 14. Click Shrink. If you did multiple objects, check the boxes next to those tables you want to fix; then click the Implement button. It asks if you just want to compact the rows in the block and leave the space out there (a good idea if you’re going to keep inserting) or if you want to release the space. Lastly, it sets up a job that you can run immediately or put into the scheduler to run at a later date. Remember, depending on the size of the object, this can cause significant overhead and time. Plain old arithmetic It takes a little math to determine whether you can release an object’s space (the same operation Enterprise Manager does in the preceding section). Before you can decide whether to make room in a table, analyze the table to gather statistics. When we say analyze, we mean analyze. The ANALYZE com- mand gets the necessary statistics to do this computation; DBMS_STATS doesn’t get those stats. 222 Part III: Caring for an Oracle Database This example uses the emp table. Do the following to analyze the table appropriately: 1. Log into SQL*Plus and type the following: < analyze table emp compute statistics;> You see this: Table analyzed. 2. Run a query against the USER_TABLES view by typing this: You should see something like this: TABLE_NAME AVG_SPACE BLOCKS ------------------------------ ---------- ---------- EMP 933 2979 As you can see, the AVG_SPACE is about 10 percent of the block size. This is normal for default block space organization. Check things like the Flash Recovery area. Any day that produces a lot of archive logs or large backup files can quickly overcome the allocated space. If you don’t have something like Enterprise Manager watching this, you can encounter problems like a hung database or failing backups. These situations can have dire consequences on your database system. Checking users Perhaps it’s maintenance. Perhaps it’s a regular security sweep. Either way, occasionally logging in to the database and checking on the connected ses- sions is beneficial. You can find things like this if you check on a regular basis: ✓ Stale sessions ✓ Login abuse such as people sharing accounts ✓ Abnormally long running jobs ✓ Unauthorized logins 224 Part III: Caring for an Oracle Database Finding stale sessions Stale sessions have been logged in to the system for a long time and no one’s done anything with them. Getting rid of stale sessions can help control resource usage. Everyone’s system is different so you have to rely on some of your own knowl- edge to decide whether the absence of activity is abnormal. To get a list of logged-in users and the last time they issued a command, connect to the data- base as a DBA user and type the following: You might see something like this: SID SERIAL# USERNAME OSUSER PROGRAM ---------- ---------- ---------- ---------- ----------------- 112 3741 MPYLE MPYLE sqlplusw.exe 122 3763 MPYLE RKHAN sqlplusw.exe 115 9853 SYSMAN oracle OMS 122 35878 HR HRAPP sqlplus@classroom 124 4 DBSNMP oracle emagent@classroom MPYLE has given his login ID to RKHAN (or at least the evidence suggests that). Evaluate this information; appropriate measures can be taken if it’s in violation of company policy. Releasing the bug We had a client system that had regularly over 3,000 connected sessions. While evaluating the sessions, we discovered that 1,200 sessions had never issued a single command after logging in and setting a date format. It turned out to be an application bug that created multiple sessions for each application operation — one of them a session to set the date format. Of course, it did no good to set a session date format and log into another session to do the work. Regardless, the client fixed the bug. It released nearly 6GB of memory from the OS! 226 Part III: Caring for an Oracle Database Checking on the backup Checking your backups should be a regular part of your daily routine. Checking backups includes these things: ✓ The database. From an Oracle DBA’s standpoint, you need to make sure the entire backup process is logged. ✓ Occasional follow up with appropriate personal about OS backups. ✓ Regular checkup to ensure the sys admin is moving the database backup from disk to tape. Too many environments put system backups on the back burner because they were scheduled jobs; no alerting was in place. If you subscribe to this methodology, you could be signing up for a heap of trouble. Keep these backup tips in mind: ✓ Oracle Recovery Manager has a LOG command that you can pass in with your backup script. This details every step of the backup as it runs. This shell script example logs the output of your RMAN backup on Linux/UNIX: #/usr/bin/ksh # Environment Settings export ORACLE_BASE=/u01/app/oracle export ORACLE_HOME=$ORACLE_BASE/product/11.1.0/db_1 export ORACLE_SID=dev11g export BAK_DATE=`date ‘+%d%b%Y_%H_%M’` export PATH=$ORACLE_HOME/bin:$PATH # Run Backup rman target / cmdfile=full_hot_backup.rmn log=full_hot_backup_${ORACLE_SID}_${BAK_DATE}.log # Check Error Code Export ECODE=$? if [ $ECODE -gt 0 ]; then mailx –s “RMAN BACKUP FAILED!” dba@perptech.com else echo “RMAN BACKUP SUCCESSFUL” fi The simple script, which you might schedule in cron, runs a backup script of your choice (called full_hot_backup.rmn) and logs the output to a file with the database name and date attached. 227 Chapter 10: Keeping the Database Running After the backup completes, the script checks whether RMAN exited cleanly. It does this by checking a mechanism called an error code. Well- written programs have this mechanism. If the environment variable $? has a value of non-zero, something failed. In this case, I have an if-then section that sends an email if that backup failed. Of course, if there’s a failure, you have to find out why and fix it. Either way, implementing a notification similar to the example helps you tighten your backup and recovery planning. ✓ Make sure the backup is usable. This is important for all backups, but is especially important if you store any backups to tape. Make sure those backups can be restored from tape and then actively recovered to a database. For obvious reasons you don’t necessarily have to do this with your production database. You can do the restore to a different database. It might be a good way to test your backup while “refreshing” a test database at the same time. Either way, as reliable as you would like to think tapes can be, you need to test them. What if one of the tape heads is going bad and writing out corrupt blocks? Doing this will also help you to practice your recovery strategies. ✓ At the very least, date and save this log in a directory on the system. If you want to go one step further, have it emailed to you every day when the backup completes. ✓ Look at the backup log for errors. Imagine how you’d feel if you experi- enced a failure and had to tell your boss that you can’t recover because the backup’s been failing for six months. It’s surprising how often we run into situations like this while helping clients with their backup and recovery strategies. Checking batch jobs Almost all companies we have worked for have some sort of nightly batch jobs that run against the database. They range from loading data, generating reports, to some sort of data processing. They might be scheduled by you or someone else. Either way, we find it common that the DBA is the one respon- sible for their monitoring and success. If you think about it, they are on your turf with you being in charge of the database and all. Whether you or someone else developed the scripts, they, like RMAN, should have some sort of logging and notification system in place. This will make it easier for you to identify a problem when it occurs. By having status emails generated and sent out, it all but forces you to keep up with the results. If your email program allows filtering, you can send the notifications to sepa- rate folders for each batch job. Just remember to check them. Again, we’re trying to help you cover all the bases that an Oracle DBA might commonly have on his or her plate. 228 Part III: Caring for an Oracle Database Audit records What’s the use of auditing in the database if you aren’t doing anything with the information? You should develop some ideas on what types of informa- tion you are looking for. In addition, regularly back up and purge the audit logs (whether they are in the database or the OS). This way, they aren’t taking up space and they are easier to search when looking for potential problems. System logs Oracle generates all kinds of system logs. Depending on what features you enabled in the database, there may be more or less. Some logs (alert and lis- tener, for example) should be regularly ✓ Checked ✓ Renamed ✓ Backed up If certain logs grow too large, it can cause problems in the database. Besides size, these logs contain valuable information sometimes that can help identify problems. In addition to Oracle’s logs, don’t hesitate to look at items like Windows Event view or the message logs on Linux/UNIX systems. They also contain valuable information. Automating Jobs with the Oracle Scheduler With the addition of the Oracle Scheduler, you can run almost any type of program with a robust resource-management and scheduling system. The scheduler can run these programs: ✓ PL/SQL Stored Procedures ✓ PL/SQL Anonymous Blocks ✓ Java Stored Programs ✓ Local and remote external programs such as shell scripts and executables 229 Chapter 10: Keeping the Database Running You can schedule jobs that are ✓ Timed-based: A job can run simply from wall-clock time. It can repeat on a schedule based on hours, days, months, and so on. ✓ Event-based: The results of certain conditions or events in the environ- ment can cause a job to run. This trigger is useful when you have to wait for other processes to finish before a job is run. ✓ Dependency-based: You can set up dependency such as success or failure. Depending on the outcome of one job, one or more dependant scenarios can be executed. Scheduler objects The scheduler can use a number of objects to run jobs. Not all of them are mandatory. These objects specify job parameters, timing, execution win- dows, and resource limits. ✓ Programs: Programs are the actual code that the scheduler will runs. They identify the execution code, arguments, and job type. ✓ Schedules: The job schedules are just want you think. They contain parameters such as when and how often. A schedule can be created and then shared for many jobs. ✓ Jobs: When a job object is created it contains the executable and the schedule required to run the job. You can the enable the job for it to begin the task based on the parameters. Jobs are categorized as: • Database runs out of the database from PL/SQL commands. • External runs off the operating system from external executables. • Chain (Dependency) runs based on status of other jobs. • Detached runs to simply kick off another job in a new process. • Lightweight are simple jobs that only exists for their immediate execution. They are not stored as schema objects. Used for quick, low-overhead applications. ✓ Windows: Helps schedule jobs for certain times which can help con- trol resource usage. When a window becomes active, certain resource directives are enabled that might restrict a job from overwhelming the system. 230 Part III: Caring for an Oracle Database Creating your first scheduler job This Oracle Scheduler example creates a simple job that runs a stored PL/SQL procedure. The procedure selects a count of the number of users on the system and inserts that number into a table with a timestamp. It runs every five minutes. Follow these steps to schedule a job for the first time: 1. Log into SQL*Plus as the SYS user. 2. Give the intended job creator the ability to create jobs: You should see this: Grant succeeded. This example job is created and run by HR. 3. Let HR see the V$SESSION table: You should see this: Grant succeeded. The _ in V_$SESSION isn’t a typo! V$SESSION is a synonym for V_$SESSION. For the grant to work, you have to give the view name. 4. Log into SQL*Plus as the job creator and make a table to hold the data: < create table user_count ( number_of_users NUMBER(4), time_of_day TIMESTAMP ) TABLESPACE users;> You see this: Table created. 5. Create a stored procedure: < CREATE OR REPLACE PROCEDURE insert_user_count AS v_user_count NUMBER(4); BEGIN SELECT count(*) INTO v_user_count FROM v$session WHERE username IS NOT NULL; 231 Chapter 10: Keeping the Database Running INSERT INTO user_count VALUES (v_user_count, systimestamp); commit; END insert_user_count; / > The stored procedure gathers the number of users and inserts them into the table with a timestamp. You should see this: Procedure created. 6. Create a program for the job: < BEGIN DBMS_SCHEDULER.CREATE_PROGRAM ( program_name => ‘PROG_INSERT_USER_COUNT’, program_action => ‘INSERT_USER_COUNT’, program_type => ‘STORED_PROCEDURE’); END; /> You see this: PL/SQL procedure successfully completed. 7. Enable the program: You see this: PL/SQL procedure successfully completed. 8. Create a schedule for the job to run: < BEGIN DBMS_SCHEDULER.CREATE_SCHEDULE ( schedule_name => ‘my_weekend_5min_schedule’, start_date => SYSTIMESTAMP, repeat_interval => ‘FREQ=MINUTELY; INTERVAL=5; BYDAY=SAT,SUN’, end_date => SYSTIMESTAMP + INTERVAL ‘30’ day, comments => ‘Every 5 minutes’); END; /> This example job runs every five minutes. You see this: PL/SQL procedure successfully completed. 232 Part III: Caring for an Oracle Database 9. Create your job with the program and schedule you defined: < BEGIN DBMS_SCHEDULER.CREATE_JOB ( job_name => ‘my_user_count_job’, program_name => ‘prog_insert_user_count’, schedule_name => ‘my_weekend_5min_schedule’); END; /> You see this: PL/SQL procedure successfully completed. 10. Enable your job so it runs within the defined schedule: < exec dbms_scheduler.enable(‘my_user_count_job’)> You see this: PL/SQL procedure successfully completed. The job runs at the specified start time (at SYSTIMESTAMP). If you choose a calendar date in the future, it doesn’t start until then. 11. After the job’s been running for 17 minutes, type the following to see your USER_COUNT table: < select * from user_count;> You see this: NUMBER_OF_USERS TIME_OF_DAY --------------- --------------------------------- 14 09-AUG-08 02.15.14.118495 PM 14 09-AUG-08 02.00.14.137300 PM 13 09-AUG-08 02.05.14.120116 PM 13 09-AUG-08 02.10.14.120680 PM Once you have the job running, you can get details about the success or failure by querying the following views: USER_SCHEDULER_JOB_RUN_DETAILS USER_SCHEDULER_JOB_LOG These views show information only about your jobs. To get information on the recent runs of our job, log in as the job creator and type this: < select job_name, status, run_duration, cpu_used from USER_SCHEDULER_JOB_RUN_DETAILS where job_name = ‘MY_USER_COUNT_JOB’;> 233 Chapter 10: Keeping the Database Running You see this: JOB_NAME STATUS RUN_DURATION CPU_USED -------------------- ---------- --------------- ------------------ MY_USER_COUNT_JOB SUCCEEDED +000 00:00:00 +000 00:00:00.01 MY_USER_COUNT_JOB SUCCEEDED +000 00:00:00 +000 00:00:00.01 MY_USER_COUNT_JOB SUCCEEDED +000 00:00:00 +000 00:00:00.00 MY_USER_COUNT_JOB SUCCEEDED +000 00:00:00 +000 00:00:00.01 Once your job is no longer needed, you have a couple of choices. Disabling a job You can easily re-enable it later. To disable your job, type the following: You should see this: PL/SQL procedure successfully completed. Removing the job Remove just the job and leave the program out there, or remove both. Same goes for the schedule you created. If you no longer need this particular job, you can remove it: You should see this: PL/SQL procedure successfully completed. If you no longer need your program, you can remove it: You should see this: PL/SQL procedure successfully completed. If you no longer need a particular schedule, you can remove it: You should see this: PL/SQL procedure successfully completed. 234 Part III: Caring for an Oracle Database The job schedule you created can be used for multiple jobs; be careful when removing your schedule. Using Oracle Data Pump Oracle Data Pump is one tool we use constantly. Data Pump is modeled after Oracle’s Export/Import tools that were available prior to Oracle 10g. Export/Import is still available but Data Pump has taken the tasks traditionally done by Export/Import and added a lot more options and flexibility. Data Pump is useful for some of these things: ✓ Moving data from one schema to another ✓ Moving data from one version of Oracle to another ✓ Moving data from one OS to another ✓ Creating Logical Backups Like the older Export/Import utilities, you must run Data Pump from the com- mand line. That makes it easy to script and schedule automated jobs. Data Pump is controlled by a series of parameters and files. You should be familiar with these files: ✓ Dump file: This file is created during a Data Pump Export. It’s the import file when you do a Data Pump Import. It’s binary so you can’t open it to see anything useful. ✓ Parfile: This optional file lists the parameters that control the Data Pump Import or Export. You create this text-based file yourself. ✓ Log file: This output is for all Data Pump Import and Export jobs unless you specify otherwise. You can name it yourself or let it have a default name. It’s useful for getting jobs statistics and for troubleshooting. You can interactively do these things with Data Pump jobs: ✓ Start ✓ Stop ✓ Pause ✓ Restart ✓ Kill 235 Chapter 10: Keeping the Database Running This means you can start a job from the command line, detach from it to do something else (while it’s still running), and re-attach later to check progress or make changes. When a Data Pump job runs into a problem, it automati- cally suspends itself; that way you have a chance to fix the problem before the job fails altogether. This can be a real time-saver. Prior to Data Pump, if an Export/Import job ran into a problem, it would fail immediately, some- times wasting hours of time. In our experience, Data Pump Export is significantly faster than traditional exports on large jobs. If you have a small job, like one or two small tables or a small schema, it doesn’t really seem to make a difference. But on large jobs, the difference is phenomenal. In one example a job took around 12 hours to dump out about 200GB with the old Export tool. When we upgraded from 9i to 11g and converted to Data Pump, it took only 45 minutes. Part of the reason is that Data Pump can be easily parallelized. Parallelizing Data Pump means starting multiple processes that run simultaneously to split up the job. The only way to parallelize tradi- tional exports is to manually split the workload into multiple jobs. That was tedious and time consuming. Data Pump Export The command line-program expdb launches Data Pump Export. All Data Pump Export jobs are “estimated” at the beginning so you see the estimate before it runs the actual export. From the OS command line, launch Data Pump Export and have it show a list of the parameter: You see something like this: Export: Release 11.1.0.6.0 - Production on Sunday, 10 August, 2008 14:30:01 Copyright (c) 2003, 2007, Oracle. All rights reserved. The Data Pump export utility provides a mechanism for transferring data objects between Oracle databases. The utility is invoked with the following command: Example: expdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp You can control how Export runs by entering the ‘expdp’ command followed by various parameters. To specify parameters, you use keywords: Format: expdp KEYWORD=value or KEYWORD=(value1,value2,...,valueN) 236 Part III: Caring for an Oracle Database Example: expdp scott/tiger DUMPFILE=scott.dmp DIRECTORY=dmpdir SCHEMAS=scott or TABLES=(T1:P1,T1:P2), if T1 is partitioned table …output snipped… You can see that Data Pump lists all the parameters you have to choose from and gives a brief explanation of each. You can specify parameters two ways: ✓ On the command line ✓ In a parameter file Go over some of the more useful parameters in detail: ✓ COMPRESSION: Modified in 11g, this parameter allows you to compress the output of Data Pump while the job is running. This is handy when space is at a premium. This parameter degrades the performance of the export but that’s to be expected. Prior to 11g, we had to compress after the job. That doesn’t do a lot of good when you don’t have the space to export the data before compres- sion. Also, while this parameter was available in 10g, it only compressed the metadata in the export. If you ask us, that’s practically useless. Now this parameter is one of the better ones available. ✓ CONTENT: This specifies what type of data you want to get. Do you want just object definitions? Do you want just the data? Both? ✓ DIRECTORY: This specifies the directory where you want the dump file to go. This is an Oracle Object directory, not a simple path on the OS. We show you how to create a directory later in this chapter. ✓ DUMPFILE: This parameter names the dump file to be output. You can also have Data Pump number the files if you like. This is handy when you use parallelism or have Data Pump break the job into multiple files of manageable size. To have Data Pump number the files, use the %U argument: DUMPFILE=my_dp_exp_%U.dmp Data Pump starts with 1 and numbers the files to 99. What if you need more than 99 files? Try something like this: DUMPFILE= my_dp_exp_seta_%U.dmp, my_dp_exp_set_b_%U.dmp 237 Chapter 10: Keeping the Database Running You can have it dump to multiple files. This is especially useful when you’re parallelizing the output. ✓ ESTIMATE: This parameter estimates your job size but won’t run it. Very handy when space is at a premium. This parameter stops the job after estimating. ✓ EXCLUDE: You can exclude certain objects from the export. For exam- ple, say you want everything but the HR and OE schemas as well as all views and functions. EXCLUDE can have multiple entries. You can say this: EXCLUDE=SCHEMAS:”’HR’,’OE’” EXCLUDE=VIEW,FUNCTION ✓ INCLUDE: Mutually exclusive with EXCLUDE, use this parameter if you want to get a specific type of object. When the list is small, this can be very useful: INCLUDE=VIEWS, TRIGGERS ✓ FILESIZE: You can break your Data Pump Export into multiple files, which aids file management. For example, if you have a 200GB export to do, you might not want a 200GB dump file to manage afterward. Instead, use this parameter to break it into 4GB chunks or something similar. ✓ FLASHBACK_TIME: If you want to dump the data from a time other than the present, you can use this parameter to specify a date and time. As long as your database still has the old data in its undo retention space, this can be very useful. ✓ NETWORK_LINK: You can connect from one database to export to another by setting up a database link and specifying it with this parameter. ✓ PARALLEL: To help speed up your dump, you can parallelize it. Try dif- ferent values to find the most efficient number of processes across dif- ferent systems. At the very least, you should be able to parallelize by the number of CPUs you have while recalling the capabilities of the storage media to which you’re writing. ✓ SCHEMAS: Gives a list of schemas to Data Pump and tells it what to get. By default, Data Pump exports the schema that’s logging in to do the job. ✓ TABLES: Restricts the export to a list of tables. ✓ TABLESPACES: Restricts the export to a list of tablespaces only. 238 Part III: Caring for an Oracle Database Data Pump Import The command-line program impdb launches Data Pump Import. From the OS command line, launch Data Pump Import and have it show a list of the parameters: You see something like this: Import: Release 11.1.0.6.0 - Production on Sunday, 10 August, 2008 15:15:49 Copyright (c) 2003, 2007, Oracle. All rights reserved. The Data Pump Import utility provides a mechanism for transferring data objects between Oracle databases. The utility is invoked with the following command: Example: impdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp You can control how Import runs by entering the ‘impdp’ command followed by various parameters. To specify parameters, you use keywords: Format: impdp KEYWORD=value or KEYWORD=(value1,value2,...,valueN) Example: impdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp …output snipped… Like Data Pump Export, Import lists the parameters that can be used with the import portion of Data Pump. Many of these parameters behave the same way they do when you’re using Data Pump Export. Take a closer look at some the Data Pump Import parameters: ✓ CONTENT: If you have a full content export file, you can choose to only import the metadata. For example, you might want to create all the tables with no rows. Obviously, if you didn’t include the rows in the export dump file, you can’t tell Data Pump Import to put them in! ✓ ESTIMATE: Estimates the size of the Data Pump Import. ✓ DIRECTORY: Tells Data Pump Import where it can find the dump file. It doesn’t have to be the same place it was dumped, but you must move the file to the new location. This might be useful when moving the file to another machine or OS. ✓ DUMPFILE: A complete listing of all the files created by Data Pump Export. 239 Chapter 10: Keeping the Database Running ✓ EXCLUDE: Works much like Data Pump Export, but tells Data Pump Import what to leave from the dump file. ✓ INCLUDE: Another way of controlling what objects are put into the target database. ✓ FLASHBACK_SCN, FLASHBACK_TIME: Use with the Data Pump Import tool only when connecting through a NETWORK_LINK. Data Pump Import can connect directly to a remote database across a database link and write the data directly into the target system. Use these parameters to pull data from the past. ✓ NETWORK_LINK: You can connect from one database and import into another by setting up a database link and specifying it with this parame- ter. No files are created when this method is used. Very handy for logical recovery and cloning. ✓ PARALLEL: Help speed up your import. ✓ REMAP_SCHEMA: This parameter is handy for copying the objects/data from one schema to another. ✓ REMAP_TABLESPACE: Moves the objects into a new tablespace. By default, they go into the same tablespace they came from. This param- eter is useful when used in conjunction with remap_schema and while moving data from one database to another. ✓ SCHEMAS: Gives a list of schemas to Data Pump to tell it what to import. By default, Data Pump imports everything in the file. In essence, you can have a full export, but then pick and choose what you want to import. ✓ TABLES: Like SCHEMAS, you can choose from your dump file what to import. ✓ TABLESPACES: You can choose what tablespaces you want import from the dump file. Creating Oracle Directories As mentioned, an Oracle directory is required for Data Pump. A directory is basically a portal to a location on the operating system. Directories are controlled by both system and object privileges. You need a system privilege, CREATE DIRECTORY, to create one. If your user doesn’t own the directory, you need READ and/or WRITE object privileges on the directory to use it. 240 Part III: Caring for an Oracle Database To create a directory, log on to the database as a user with appropriate privi- leges and type the following: create directory my_data_pump_dir as ‘/u01/app/oracle/dumpfiles’; You should see this: Directory created. Using Data Pump with a Parameter File A parameter file is a text file listing the parameters for the Data Pump Export or Import and setting the chosen values. Data Pump Export and Import parameter files are constructed the same way. Follow these steps to run a Data Pump Export with this parameter file: 1. Type the parameter file into a text editor and save it to a directory. This example is a parameter file that exports the DEPARTMENTS and EMPLOYEES tables of the HR schema: # File: /u01/app/oracle/scripts/datapump/my_data_pump_parfile.par DIRECTORY=my_data_pump_dir DUMPFILE=my_data_pump_dumpfile.dmp LOGFILE=my_data_pump_logfile.log SCHEMAS=HR TABLES=EMPLOYEES, DEPARTMENTS COMPRESSION=ALL 2. Open a command-line prompt and go to the directory where your parameter file is saved. 3. Launch Data Pump Export with your parameter file: You should see this: Export: Release 11.1.0.6.0 - Production on Sunday, 10 August, 2008 16:53:33 Copyright (c) 2003, 2007, Oracle. All rights reserved. Username: 241 Chapter 10: Keeping the Database Running 4. Type in the username and give the password for the user you want to export with. You should see something like this: Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Starting “SYS”.”SYS_EXPORT_SCHEMA_01”: /******** AS SYSDBA parfile=my_ data_pump_parfile.par Estimate in progress using BLOCKS method... Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA Total estimation using BLOCKS method: 128 KB …output snipped… . . exported “HR”.”DEPARTMENTS” 5.437 KB 27 rows . . exported “HR”.”EMPLOYEES” 8.726 KB 107 rows Master table “SYS”.”SYS_EXPORT_SCHEMA_01” successfully loaded/unloaded ************************************************************************** **** Dump file set for SYS.SYS_EXPORT_SCHEMA_01 is: /u01/app/oracle/dumpfiles/MY_DATA_PUMP_FILE.DMP Job “SYS”.”SYS_EXPORT_SCHEMA_01” successfully completed at 16:49:25 5. Create the user and the tablespace. Make sure both users have the same privileges. 6. Create a parameter file that imports the data into a new user in its own tablespace. In this example HR2 is imported to its own tablespace, HR2_DATA. Since this is also only a partial piece of the HR data model, you exclude constraints and triggers; they have dependent objects that aren’t in the export dump file. You don’t have to exclude them, but you get an error in the log file as Data Pump tries to create them. Such a parameter file might look like this: # File: /u01/app/oracle/scripts/datapump/my_HR2_data_pump_parfile.par DIRECTORY=my_data_pump_dir DUMPFILE=my_data_pump_file.dmp LOGFILE=my_HR2_data_pump_logfile.log EXCLUDE=CONSTRAINT EXCLUDE=TRIGGER REMAP_SCHEMA=HR:HR2 REMAP_TABLESPACE=EXAMPLE:HR2_DATA 242 Part III: Caring for an Oracle Database 7. Run the import: You should see something like this: Import: Release 11.1.0.6.0 - Production on Sunday, 10 August, 2008 17:39:35 Copyright (c) 2003, 2007, Oracle. All rights reserved. Username: / as sysdba Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Master table “SYS”.”SYS_IMPORT_FULL_01” successfully loaded/unloaded Starting “SYS”.”SYS_IMPORT_FULL_01”: /******** AS SYSDBA parfile=my_hr2_ data_pump_parfile.par Processing object type SCHEMA_EXPORT/USER Processing object type SCHEMA_EXPORT/TABLE/TABLE Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA . . imported “HR2”.”DEPARTMENTS” 5.437 KB 27 rows . . imported “HR2”.”EMPLOYEES” 8.726 KB 107 rows …output snipped… Job “SYS”.”SYS_IMPORT_FULL_01” successfully completed at 17:39:53 If the user is someone other than the schema you’re exporting, you need one of these two things: ✓ DBA privileges ✓ The DATAPUMP_EXP_FULL_DATABASE role If you’re going to import into a user other than the one you’re running the job with, you need one of these two things: ✓ DBA privileges ✓ The DATAPUMP_IMP_FULL_DATABASE role By default, the log file is created in the same directory as your dump file. The logfile is a text file that any text editor can read. Chapter 11 Tuning an Oracle Database In This Chapter ▶ Nailing tuning basics ▶ Gathering with Automatic Workload Repository (AWR) ▶ Using utomatic Database Diagnostic Monitor (ADDM) ▶ Tuning into SQL ▶ Understanding 10046 trace event with TKPROF Oracle performance tuners have an indistinguishable systematic approach that compares to any real-world tuning effort, Oracle or other. Regardless of the method used to tune Oracle, base your goals on the needs of the business or purpose of the application. In this chapter we cover the methods, concepts, and tools necessary for Oracle 11g performance tuning. We show you the commonly used methods to diagnose and alleviate Oracle 11g performance issues. You also discover how to apply this knowledge to proactive tuning principles. Evaluating Tuning Problems Tuning problems are usually related to poorly designed applications. Hardware upgrades aren’t normally the all-saving remedy. Although hardware architecture does have a place in a basic tuning discussion, it’s not necessarily the remedy. As a novice to Oracle or a decision maker, exhaust all affordable options before giving in to the “You need more hardware” or the generic Oracle support comment, “You need to upgrade.” 244 Part III: Caring for an Oracle Database Although system hardware — the components all working toward the same goal in supporting the business — can be an area of focus for Oracle tuning, it can indirectly become a piece of the problem. These expensive hardware com- ponents, shown in Figure 11-1, include the following but are not limited to: ✓ Servers, such as hosts, nodes, and boxes ✓ Network routers and data switches ✓ Disk storage (Storage Area Networks [SAN]) or Network Attached Storage (NAS) and less-expensive storage arrays Hopefully, these hardware components have been optimized to support the applications that use them. Hardware performance can be attributed to the use of CPU, I/O, memory, and network. Generally speaking, as hardware usage increases, performance degrades aggregately, meaning that as you get closer to 100 percent usage thresholds, the worse the hardware will perform. Because hardware compo- nents are somewhat dependent on each other, they can affect the host’s overall performance. Operating specific utilities and DB Console can help you determine how a host is performing during peak activity. Figure 11-1: Standard tiered archi- tecture. Web server layer New application servers Application server layer Virtual database server layer Virtual SAN disk layer 245 Chapter 11: Tuning an Oracle Database The 11g reactive tuning basics are actually straightforward: 1. Identify the issue(s) based on your business’s process requirements. Front-line users send you emails saying that things are running slowly. The billing manager calls complaining that the billing cycle took three hours longer than normal. The real determining factor to investigate a perceivable performance issue is a business decision. What is most important to the business? The billing cycle finishing in a specified period or that front-line users have priority during the most active peri- ods? The answer is usually both. Always be truthful, and be sure to inform senior management if you are going to do something questionable, such as scheduling a backup or building an index during important processing hours. Don’t lose your credibility by not being forthcoming. Adversely, don’t be a cowboy in production. 2. Establish the tuning goal. Ensure that your tuning goals are focused toward the issue(s). If it’s not broken, then don’t try to fix it. Concentrate your efforts on determining the root cause. 3. Determine the best method to resolution. Form the plan by documenting your reasoning of the root cause and how you plan to resolve it. Share the plan with your counterparts and management. Include any special circumstances or risks. Be prepared to articulate your reasoning. A strong contingency plan is helpful in keep- ing people out of your cubicle. 4. Test your plan. Your plan might be a simple tweak, or it may involve a combination of adjustments that will hopefully make you a superstar. Most test plans aren’t capable of performing an apples-to-apples test, so you need to feel confident with your plan. Keep in mind that your plan may involve mul- tiple, time-consuming tests and retests. A new 11g feature, Database Replay, can help you with testing. We cover Database Replay in detail in Chapter 14. 5. Execute your plan. Stop holding your breath. You did your research and hopefully tested adequately. You need to document your results and compare them to the expected baseline or service level. This documentation is useful when quantifying your positive impact to the organization. 246 Part III: Caring for an Oracle Database Tuning Your Database A performance-minded DBA focuses on IO throughput (contention relief), memory, and CPU usage. Oracle 11g captures OS and database statistical information so that you can find most performance-based issues by access- ing Automatic Workload Repository (AWR) with Automatic Database Diagnostic Monitor (ADDM), SQL Tuning Sets, V$ views plus the hosts CPU, I/O, and memory usage. Tuning techniques for 11g are driven toward utilizing AWR. In addition, you can examine other performance items at the database system level, such as init.ora parameters that the Oracle kernel controls. Oracle init.ora performance-tuning parameters can have a major impact on how Oracle thinks. Before making any init.ora changes for performance, do your homework and test your theory because simple changes can negatively affect an 11g database. Certain parameter changes can greatly influence how queries are executed in the database via the Cost-Based Optimizer (CBO). The good news is that Oracle 11g can manage some memory structures auto- matically to help reduce the pressure on the DBA. In addition, some init.ora parameters are derived from the OS and are most likely accurate and don’t require adjusting. 11g’s Automatic Memory Management allows Oracle to manage all the data- base memory. It can allocate and deallocate memory between the System Global Area (SGA) and the Program Global Area (PGA) according to the data- base activity. This memory management configuration is recommended by Oracle and was also discussed in Chapter 2. To turn on Oracle’s Automatic Memory Management, set the following init parameters in the database init.ora or spfile.ora initialization file and then restart the database instance: ✓ MEMORY_MAX_TARGET=nM: Maximum amount memory for Oracle to use in megabytes. ✓ MEMORY_TARGET=nM: Initial memory to use in megabytes but can’t exceed the value of MEMORY_MAX_TARGET. It should include the com- bined size of the SGA and the PGA. • SGA_TARGET=0 • PGA_AGGREGATE_TARGET= ✓ DB_BLOCK_SIZE: Sets the size of how the Oracle blocks are stored and scanned for reads in the database. Typical size is 8192 or 8k. Warehouses databases can jump to a 32k block size. This parameter can drastically affect performance. 247 Chapter 11: Tuning an Oracle Database ✓ SGA_TARGET: Sets the total memory size for these things: • Buffer cache (Data blocks in memory) • Java pool (Java in memory) • Large pool (Large PL*SQL statements) • Share pool (Parsed SQL statements in general) If you’re using Automatic Memory Management, then you would set SGA_TARGET=0 and then set MEMORY_TARGET=nM – where n is a value of the SGA and PGA combined in megabytes. ✓ OPTIMIZER_INDEX_COST_ADJ: Sets the amount of effort Oracle will use to look for an index to help resolve a query. Setting the value too high can kill performance. It ranges from 1 to 1000; the default is 100. ✓ DB_FILE_MULTIBLOCK_READ_COUNT: Sets the number of blocks that are read in a single I/O. If you set this number to a higher value, Oracle may think that a full table scan is quicker than an index lookup scan. Default is 8, but most systems are set to 32. Consider storage system stripe sizes with this parameter. ✓ PGA_AGGREGATE_TARGET: Sets automatic controls on the amount of memory used for sorting large queries. Sorting to disk is very costly compared to memory. Finding a balance between large and small sorts can be challenging. PGA_AGGREGATE_TARGET isn’t set if using Automatic Memory Management. ✓ LOG_BUFFER: Sets the amount of memory Oracle uses to buffer redo entries before writing them to the redo log files. This is often an I/O contention problem that you can resolve by increasing the value. Default is this formula: 512KB or 128KB × Number of CPUs on the Server (whichever is greater). Gathering Performance Information with Automatic Workload Repository Automatic Workload Repository (AWR) is a combination of performance utili- ties used to gather performance information. It has built-in automated mecha- nisms to capture real-time statistics that are continually captured and written to the AWR tables once an hour by default. These statistics, called snapshots, accumulate into a series of performance snapshots you can comb through to evaluate database performance. By default, the snapshots are retained for 8 days, but you’re encouraged to modify the retention period to at least 30 days if plenty of space is available in the sysaux tablespace. You can modify the interval period as well. 248 Part III: Caring for an Oracle Database A typical size guesstimate for AWR data using an 8-day cycle and 1-hour interval snaps with moderate activity is 200MB to 400MB. Decreasing the interval period or increasing the retaining period will require more space. To be safe, ensure that you have plenty of space in the sysaux tablespace and that the data files are set to autoextend. Keep an eye on the growth so it doesn’t become a problem. Technically, AWR is licensed with the enterprise version of Oracle 11g. Verify your license agreements before using it. You can change the AWR snapshots two ways: ✓ SQL*Plus method: Good for novices that use SQL*Plus on the server the database instance resides on ✓ Database Control method: The GUI web tool, which is fairly intuitive and best for those with no 11g experience SQL*Plus method Here’s how to implement the SQL*Plus method. 1. Connect to SQL*Plus with DBA privileges. You must have DBA privileges to execute these commands, so log in as a user with DBA role or as SYSDBA. 2. Execute the following to change the AWR snapshot increment from the 1-hour default to 30 minutes: BEGIN DBMS_WORKLOAD_REPOSITORY.modify_snapshot_settings( retention => 43200, -- Minutes (= 30 Days) interval => 30); -- Minutes END; / 3. To delete a previous set of snapshots, execute the following example in SQL*Plus listing the range to delete: BEGIN DBMS_WORKLOAD_REPOSITORY.DROP_SNAPSHOT_RANGE(1,2528); END; / 249 Chapter 11: Tuning an Oracle Database After you have snapshots to work with, you can run AWR reports manu- ally by executing the following script in SQL*Plus. It’s interactive and gives you a choice of which consecutive snapshots you’d like to include in the report, which format you’d like to see it in (HTML or text), and lastly, a choice of file name. 4. To view the text or HTML-based AWR information manually, use the following example: SQL> @$ORACLE_HOME/rdbms/admin/awrrpt.sql Current Instance ~~~~~~~~~~~~~~~~ DB Id DB Name Inst Num Instance ----------- ------------ -------- ------------ 3881932609 DEV11G 1 dev11g Specify the Report Type ~~~~~~~~~~~~~~~~~~~~~~~ Would you like an HTML report, or a plain text report? Enter ‘html’ for an HTML report, or ‘text’ for plain text Defaults to ‘html’ Enter value for report_type: text Instances in this Workload Repository schema ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DB Id Inst Num DB Name Instance Host ------------ -------- ------------ ------------ ------------ * 3881932609 1 DEV11G dev11g classroom Using 3881932609 for database Id Using 1 for instance number Specify the number of days of snapshots to choose from ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Entering the number of days (n) will result in the most recent (n) days of snapshots being listed. Pressing without specifying a number lists all completed snapshots. Enter value for num_days: 250 Part III: Caring for an Oracle Database Listing all Completed Snapshots Snap Instance DB Name Snap Id Snap Started Level ------------ ------------ --------- ------------------ --- dev11g DEV11G 180 26 Mar 2008 01:00 1 181 26 Mar 2008 02:00 1 182 26 Mar 2008 03:00 1 377 03 Apr 2008 06:00 1 Ö 379 03 Apr 2008 08:00 1 380 03 Apr 2008 09:00 1 381 03 Apr 2008 10:00 1 Specify the Begin and End Snapshot Ids ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Enter value for begin_snap: 378 Begin Snapshot Id specified: 378 Enter value for end_snap: 380 End Snapshot Id specified: 380 Specify the Report Name ~~~~~~~~~~~~~~~~~~~~~~~ The default report file name is awrrpt_1_378_380.txt. To use this name, press to continue, otherwise enter an alternative. Enter value for report_name: $HOME/awr7to9.txt After entering the fully qualified report name, you see a large amount of data scroll by. You may now view the report, which contains most of the statistical information during the period of 7a.m. to 9 a.m. It contains CPU, IO, memory, and network usage. It also shows more detailed Oracle memory usage, wait events, and top-running SQL statements that are taking the most time and resources. This report is quite handy in pin- pointing particular times that the database was sluggish. Database Control method You can also run an AWR report by running the awrrpti.sql script. To use the Database Control method, simply access the DB Control web site that was created when you installed the database: 1. From the database home, click Server. 2. Under the Statistics Management area, click Automatic Workload Repository. 3. Click Run AWR Report. 251 Chapter 11: Tuning an Oracle Database 4. Choose a beginning period and click OK. 5. Choose an ending period and click OK. You see a racing clock and the words Creating Report. The screen refreshes shortly after with the AWR report. Figure 11-2 is snippet of the web-based AWR report created by using DB Control. Figure 11-2: DB Console AWR report. 252 Part III: Caring for an Oracle Database Using the Automatic Database Diagnostic Monitor (ADDM) You can run the Automatic Database Diagnostic Monitor (ADDM) on your data- base’s current performance or based on a specific set of AWR snapshots for previous performance analysis. To access ADDM information (technically, it’s just AWR data that Oracle analyzes and then provides recommendations on), you must first create a report. You can create a report by simply using the Database Control web site or by running the addmrpt.sql or the addmrpti.sql script, which runs in similar fashion to the previous awrrpt.sql example. The addmrpt.sql script creates an ADDM report based on the current AWR information where the addmrpti.sql script prompts you for a beginning and ending AWR snapshot and then analyzes the performance between them: SQL> @$ORACLE_HOME/rdbms/admin/addmrpti.sql The resulting report shows you areas of impact that you can further research for improvement. To access or review ADDM through DB Console, follow these steps: 1. From the database home using the DB Console web site, click Server. 2. In the Related Links area, click Advisor Central. 3. Under Advisors, click ADDM. 4. Choose Run ADDM to analyze past performance. The current performance option creates a snapshot immediately and then runs ADDM against it. 5. Choose the AWR snapshot beginning and ending time, which are listed. The time to create the report depends on the activity within each snap- shot period and the number of snapshots used in the set being analyzed. 6. Click OK. 253 Chapter 11: Tuning an Oracle Database 7. If Database Control asks whether you’re sure you want to exit, click Yes. The ADDM screen appears. You can now view specific and summarized information of your ADDM run. The basic analysis will be a few findings, recommendations for the findings, and actions for the recommenda- tions. Figure 11-3 is an example of the ADDM results. Figure 11-4 is the actual ADDM report with recommendations. Figure 11-3: ADDM example. 254 Part III: Caring for an Oracle Database Figure 11-4: ADDM_ report.txt. ADDM Report for Task 'TASK_1455' -------------------------------- Analysis Period --------------- AWR snapshot range from 1118 to 1304. Time period starts at 02-JUN-08 03.00.59 AM Time period ends at 09-JUN-08 08.15.07 PM Analysis Target --------------- Database 'DEV11G' with DB ID 3884432576. Database version 11.1.0.6.0. ADDM performed an analysis of instance dev11g, numbered 1 and hosted at classroom.perptech.local. Activity During the Analysis Period ----------------------------------- Total database time was 5120 seconds. The average number of active sessions was .01. Summary of Findings ------------------- Description Active Sessions Recommendations Percent of Activity ---------------------------------- ------------------- --------------- 1 Top SQL by DB Time 0 | 30.61 5 2 "User I/O" wait Class 0 | 16.07 0 3 Hard Parse 0 | 12.35 0 4 CPU Usage 0 | 11.77 2 5 Commits and Rollbacks 0 | 8.52 2 6 PL/SQL Execution 0 | 6.58 4 7 Hard Parse Due to Parse Errors 0 | 3.27 1 8 Top Segments by I/O 0 | 2.55 1 9 Soft Parse 0 | 2.24 2 10 Hard Parse Due to Sharing Criteria 0 | 2.17 1 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Findings and Recommendations ---------------------------- Finding 1: Top SQL by DB Time Impact is 0 active sessions, 30.61% of total activity. ------------------------------------------------------ SQL statements consuming significant database time were found. Recommendation 1: SQL Tuning Estimated benefit is 0 active sessions, 17.1% of total activity. ---------------------------------------------------------------- Action Investigate the SQL statement with SQL_ID "b6usrg82hwsa3" for possible performance improvements. Related Object SQL statement with SQL_ID b6usrg82hwsa3. call dbms_stats.gather_database_stats_job_proc ( ) Rationale SQL statement with SQL_ID "b6usrg82hwsa3" was executed 15 times and had an average elapsed time of 58 seconds. 255 Chapter 11: Tuning an Oracle Database Recommendation 2: SQL Tuning Estimated benefit is 0 active sessions, 5.5% of total activity. --------------------------------------------------------------- Action Tune the PL/SQL block with SQL_ID "6gvch1xu9ca3g". Refer to the "Tuning etc. etc. etc. Finding 10: Hard Parse Due to Sharing Criteria Impact is 0 active sessions, 2.17% of total activity. ----------------------------------------------------- SQL statements with the same text were not shared because of cursor environment mismatch. This resulted in additional hard parses which were consuming significant database time. Common causes of environment mismatch are session NLS settings, SQL trace settings and optimizer parameters. Recommendation 1: Application Analysis Estimated benefit is 0 active sessions, 2.17% of total activity. ---------------------------------------------------------------- Action Look for top reason for cursor environment mismatch in V$SQL_SHARED_CURSOR. Symptoms That Led to the Finding: --------------------------------- Hard parsing of SQL statements was consuming significant database time. Impact is 0 active sessions, 12.35% of total activity. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Additional Information ---------------------- Warnings -------- The optimal memory target for the instance could not be determined because the value of "memory_target" changed during the analysis period. Miscellaneous Information ------------------------- Wait class "Application" was not consuming significant database time. Wait class "Concurrency" was not consuming significant database time. Wait class "Configuration" was not consuming significant database time. Wait class "Network" was not consuming significant database time. Session connect and disconnect calls were not consuming significant database time. The database's maintenance windows were active during 32% of the analysis period. Improving Queries with SQL Tuning Tuning methods use 11g utilities to identify and reduce the heavy workload of resource-intensive SQL statements. Oracle 11g uses an execution plan to resolve queries and is the driving decision maker behind the Oracle query optimizer. This engine uses the most efficient (least cost) way for the 256 Part III: Caring for an Oracle Database database to resolve a query. For example, it may be more efficient (cheaper) for Oracle to complete a full table scan than to do an index lookup followed by a partial table scan. The optimizer generates the execution plan before it runs the query for the first time. (For information on how the SQL plan management will store the plan, see the section “SQL Profiling and Plan Management,” later in this chapter.) Keep the business process in perspective. A report may take hours to complete and more time to tweak. The report may benefit from more tuning, but the busi- ness focus can be on concurrent user response time versus long-running reports. Concentrate on the business objective. In addition to the AWR and ADDM reports described earlier in this chapter, several other good tools are available for 11g SQL tuning: ✓ Explain plan ✓ Active Session History (ASH) ✓ SQL Access Advisor ✓ SQL Tuning Advisor ✓ SQL Profiling and Plan Management Explain plan Oracle’s explain plan is a simple tool used to view the execution plan that Oracle’s query optimizer chooses in resolving a query. Oracle can make poor decisions on how best to resolve a query, and you need the ability to make adjustments that will allow the query to run more efficiently. The following steps create a table where the query execution results are stored. The table is then selected against to review the output. In addition, a simpler method called autotrace can be used and is illustrated here: 1. Create the plan table by connecting to SQL*Plus with DBA privileges: SQL> CONNECT sys/password AS SYSDBA Connected SQL> @$ORACLE_HOME/rdbms/admin/utlxplan.sql Table created. 2. Grant privileges on the plan table to public (all): SQL> GRANT ALL ON sys.plan_table TO public; Grant succeeded. 257 Chapter 11: Tuning an Oracle Database 3. Create a public synonym for the table: SQL> CREATE PUBLIC SYNONYM plan_table FOR sys.plan_table; Synonym created. Figure 11-5 shows a good example of an explain plan output. Notice the full table scans? An index or two may be in order. Figure 11-5: Explain plan. 258 Part III: Caring for an Oracle Database Active Session History (ASH) Active sessions in the database with significant execution elapsed time are sampled every second and are stored with plan execution details in memory for a period of time. The amount of time depends on the activity in the database. They’re then flushed to disk. You can find active information in the V$ACTIVE_SESSION_HISTORY view. Session information flushed to disk appears in the DBA_HIST_ACTIVE_SESS_HISTORY view. This information allows you to examine session data and avoid additional time-consuming tracing steps as discussed in the section “SQL Profiling and Plan Management” later in this chapter. To run the ASH report, simply use the following script. It requests a beginning and ending time and then reports the activity in between. SQL> @$ORACLE_HOME/rdbms/admin/ashrpt.sql Follow along to access or review ASH through the DB Console: 1. From the database home using the DB Console web site, click Performance. 2. Click Top Activity. 259 Chapter 11: Tuning an Oracle Database 3. Click Run ASH Report. 4. Choose a beginning and ending time. 5. Click Generate Report. Think of ASH as your own private AWR reports. Instead of looking at all data- base load activity, you’re only looking at your own. SQL Access Advisor SQL Access Advisor is a tuning tool that can assist you in determining whether indexes, partitions, or materialized views would improve perfor- mance. It’s a cumbersome and time-consuming process, and we only want to bring to your attention how it works and that it’s there for your downtime pleasure. Setting up SQL Access Advisor to run effectively requires structural statis- tics. Gathering estimated statistics is normally a nightly scheduled task if the workload and the size of the database allow time for it. Statistics are very important for this tool to work effectively. How does SQL Access Advisor work? You must create an Access task to define the advisory parameters to be used during a workload on the data- base. SQL Access Advisor analyzes the statistics and workload together to generate recommendations. You can then review these recommendations and implement them in the database. To navigate to SQL Access Advisor through the DB Console: 1. From Database Home using the DB Console web site, click Server. 2. Click Advisor Central. 3. Click SQL Advisors. 4. Click SQL Access Advisor. SQL Tuning Advisor You can use SQL Tuning Advisor to find issues with one or many costly SQL statements that have already been identified as issues. SQL Tuning Advisor tasks are run nightly by default when you create or migrate a database with 11g. The task called sys_auto_sql_tuning_task runs every night to find heavy load SQL statements and tries to find ways to increase their performance. It can provide beneficial recommendations on one or more SQL statements with the automatic tuning advisor. 260 Part III: Caring for an Oracle Database You must first create a tuning set when using multiple SQL statements. The recommendations are in the form of SQL text or a SQL profile (see the next section). You can then restructure or accept the SQL or the plan to imple- ment the new changes. Set the initialization parameter STATISTICS_LEVEL to TYPICAL (default) or ALL. Setting it to BASIC disables automatic SQL tuning. ADDM also requires the CONTROL_MANAGEMENT_PACK_ACCESS initialization parameter to be set to DIAGNOSTIC+TUNING (default), or it will be disabled. To navigate to SQL Tuning Advisor through the DB Console: 1. From Database Home using the DB Console web site, click Server. 2. Click Advisor Central. 3. Click SQL Advisors. 4. Click SQL Tuning Advisor. Figure 11-6 is a view of the main SQL Advisors page. You can click one of the following sources, which will take you to the location where you can use the SQL Tuning Advisor: ✓ Top Activity ✓ Historical SQL (AWR) ✓ SQL Tuning Sets ✓ Snapshots ✓ Preserved Snapshot Sets SQL Profiling and Plan Management The query optimizer can sometimes produce inaccurate execution plans due to missing, stale, or incomplete statistics and context information (stuff that helps form an execution plan). Traditionally, DBAs have corrected this prob- lem by manually adding Oracle hints to the application code, which forces the optimizer to adjust its plan. Here is a common index hint: select /*+ INDEX(emp_city idx_job_code) */ emp_name, job_code from emp where job_code = ‘D’; 261 Chapter 11: Tuning an Oracle Database Figure 11-6: SQL Advisors page. For Commercial, off-the-shelf (COTS) packaged applications, changing the application code violates support agreements. The only alternative available is to log a request with the application vendor, which may take weeks, or you can use SQL profiles and SQL Plan Management (SPM). SQL profile generates stats and creates recommendations that are tested against the database during nightly maintenance windows. You can auto- matically implement these profiles by setting the advisory parameter to ACCEPT_SQL_PROFILES=TRUE. To set this parameter, you must use the DBMS_SQLTUNE package: BEGIN DBMS_SQLTUNE.set_tuning_task_parameter( task_name => ‘SYS_AUTO_SQL_TUNING_TASK’, parameter => ‘ACCEPT_SQL_PROFILES’, value => ‘TRUE’); END; / With SPM, the optimizer manages the plans automatically and verifies that only accepted plans are used. New plans are accepted only if the current plan is outperformed by the newly generated one, which causes SQL plans to evolve over time. SQL plans can become outdated if the data changes drasti- cally or if particular initialization parameters are adjusted. Profiling and Plan Management help eliminate the manual processes used to manage SQL statements. The accepted plans can then be migrated to a test database for further testing using newer hardware or by using different init. ora parameters. 262 Part III: Caring for an Oracle Database 10046 trace event Event 10046, a previously unpublished Oracle event, is a tracing mechanism used to find SQL performance issues. Oracle support and DBAs often need to pinpoint or know more about the database performance than the explain plan or sql_trace have to offer. Event 10046 triggers Oracle to log the raw information about the decisions that the Oracle kernel and the optimizer are making to resolve or respond to a session’s activities. These timing measurements and wait events are reflected in a trace file, which can help identify specific bottlenecks that may not have been identified using other performance-tuning means. The event information is written to a trace file under the 11g diagnostic destination (init parameter diagnostic_dest, which is ‘(volume_name)/diag/rdbms/(database_name)/(sid_ name)/trace’). The information can also include the bind variable values. You can set the 10046 event for a given session in several ways. You don’t need to alter a session to set TIMED_STATISTICS=TRUE and set MAX_DUMP_FILE_ SIZE=UNLIMITED if they were previously set in the init.ora startup file. You can also trace the database level with this event as opposed to the session level. Tracing with event 10046 writes large amounts of content to the trace file. Be sure that the volume or disk that contains the diag directory has plenty of space available. We’re talking about a monstrous size file. Be sure to turn it off when you’re done with the trace. The following example reflects a technique to start 10046 tracing: SQL> alter session set events ‘10046 trace name context forever, level number’; The following mini table lists values for the levels that you can use for the 10046 event. 0 No statistics 1 Basic statistics and the same as setting sql_trace=true 4 Same as level 1 except adds BIND section 8 Same as level 1 except with wait events 12 Combines levels 1, 4, and 8 Here’s how to turn on timing if it’s not already set at the database level: SQL> alter session set timed_statistics=true; 263 Chapter 11: Tuning an Oracle Database You also need to set tracing to unlimited, or you may get an incomplete trace file when dump file size limit is reached: SQL> alter session set max_dump_file_size=unlimited; Setting the TRACEFILE_IDENTIFIER is optional but recommended to help identify trace files when you go looking for them. You can use the TRACEFILE_ IDENTIFIER before you start the tracing to later help identify your trace file in the trace directory. SQL> alter session set tracefile_identifier=’MYSESSION’; The following code sets extended SQL trace to level 8. (See the previous table, which describes the various trace levels.) SQL> alter session set events ‘10046 trace name context forever, level 8’; Now that tracing is set up, you execute the SQL statements you want to review. During this SQL execution, the raw data to be analyzed by the tool is generated. This command disables tracing: SQL> alter session set events ‘10046 trace name context off’; To trace another user session, you need to find the SID and serial# of the session you want to trace. To find a session to trace, run the following SQL*Plus statement: set linesize 200 select username, sid SID, serial#, osuser, program, status, to_char(logon_time,’MM/DD/YYYY hh24:mi’)Logon_time from v$session where serial# <> ‘1’ and status = ‘ACTIVE’ and username like upper(‘%&user%’) order by logon_time / Once you have the SID and serial number of the session you want to trace, you can use Oracle-supplied packages to start and stop the tracing. This example is the DBMS_SYSTEM package: SQL> execute sys.dbms_system.set_bool_param_in_session (&&SID, &&SERIAL,’timed_ statistics’,true); 264 Part III: Caring for an Oracle Database This statement turns timing on if it’s not already set at the database level: SQL> execute sys.dbms_system.set_int_param_in_session (&&SID, &&SERIAL, ‘max_dump_file_size’,10000000); This syntax sets tracing to a very large value of 10,000,000. Otherwise, you may get an incomplete trace file when dump file size limit is reached. SQL> execute sys.dbms_system.set_ev(&&SID, &&SERIAL, 10046, 8, ‘ ‘); This code sets extended SQL trace to level 8. See the previous table for information on all trace levels. Execute the SQL statements you want to test. During this execution, the statements are being traced. This statement disables tracing: SQL> execute sys.dbms_system.set_ev(&&SID, &&SERIAL, 10046, 0, ‘ ‘); The DBMS_SUPPORT package is preferred and fully supported by Oracle but the preceding DBMS_SYSTEM works just fine. You have to install the DBMS_SUPPORT package, but it isn’t available on all platforms. To install, run the dbmssupp.sql script as sysdba located in $ORACLE_HOME/rdbms/ admin directory. Examples of using DBMS_SUPPORT instead of DBMS_ SYSTEM include: SQL> execute sys.dbms_support.start_trace_in_session (&&SID, &&SERIAL, waits=>true, binds=>false); The following statement is equivalent to setting SQL trace to level 8. Level 12 tracing can be established by setting binds=>true. Execute your SQL statements you want to test. During this execution, the statements are being traced. Once you execute all the SQL statements you want to trace, stop the tracing process: SQL> execute sys.dbms_support.stop_trace_in_session(&&SID, &&SERIAL); In some applications, it may be difficult to start tracing because of physical timing (catching the session before it starts running SQL) or because a ses- sion is using connection pooling, therefore; a logon trigger may help. Just enable it only for as long as needed because it can cause a performance problem in heavily used systems. The user that creates the trigger must be granted alter session explicitly. 265 Chapter 11: Tuning an Oracle Database Tweak the following example to ensure that you trace only the session you are trying to capture or tune: CREATE OR REPLACE TRIGGER SYS.enable_10046_trace_trigger AFTER LOGON ON DATABASE -- 10046 TRACELEVELS -- 0 - Turn off tracing. -- 1 - Basic SQL_TRACE. -- 4 - Level 1 plus Bind Variables. -- 8 - Level 1 plus wait events. -- 12 - Level 1 plus Bind/Wait event information. DECLARE v_exe v$session.program%TYPE; v_sid v$session.SID%TYPE; v_osuser v$session.osuser%TYPE; v_machine v$session.machine%TYPE; v_ok VARCHAR (10); BEGIN -- Get user SID information SELECT SID INTO v_sid FROM v$mystat WHERE ROWNUM < 2; -- Get Program executable for this session SELECT program INTO v_exe FROM v$session WHERE SID = v_sid; -- Get OSUSER Details SELECT osuser INTO v_osuser FROM v$session WHERE SID = v_sid; -- Get Machine Details SELECT machine INTO v_machine FROM v$session WHERE SID = v_sid; IF USER = ‘ACCESS_USER’ AND v_exe = ‘access.exe’ AND v_osuser = ‘cartman’ and v_machine=’Win_Machine4’ THEN EXECUTE IMMEDIATE ‘alter session set timed_statistics=true’; EXECUTE IMMEDIATE ‘alter session set max_dump_file_size=unlimited’; EXECUTE IMMEDIATE ‘alter session set tracefile_identifier=’’session_trace_trigger’’’; EXECUTE IMMEDIATE ‘alter session set events ‘’10046 trace name context forever, level 8’’ ‘; DBMS_SESSION.set_identifier (‘SQL TRACE ENABLED VIA LOGIN TRIGGER’); END IF; END; 266 Part III: Caring for an Oracle Database Examining the trace file is a little less complex than interpreting the ancient Mayan language. Oracle offers a tool called TKPROF that you can use to format trace files into something a little more legible. It can sort trace infor- mation into more specific areas, such as CPU or I/O. Some experienced Oracle performance tuners prefer to read trace files in their raw formats because TKPROF can skew the raw data by bundling items into a non-time sequential format. But overall, TKPROF can reduce the time it takes to research the trace information. To execute TKPROF, use the tkprof command-line utility. Execute the utility in the same directory your trace file lives. You specify the following things: ✓ The name of the trace file to analyze ✓ The name of the output file ✓ The database username and password that has a plan table It is common to specify sys=no and waits=yes to suppress unnecessary system statements and to include database wait information. Here’s an example of how to run TKPROF and a partial view of what a TKPROF trace file looks like: unix> tkprof dev11g_ora_18892.trc tk_trace.txt explain=system/Indy_500$$$ sys=no waits=yes unix> more tk_trace.txt TKPROF: Release 11.1.0.6.0 - Production on Wed Jun 11 21:51:37 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. Trace file: dev11g_ora_18892.trc Sort options: default ******************************************************************************** count = number of times OCI procedure was executed cpu = cpu time in seconds executing elapsed = elapsed time in seconds executing disk = number of physical reads of buffers from disk query = number of buffers gotten for consistent read current = number of buffers gotten in current mode (usually for update) rows = number of rows processed by the fetch or execute call ******************************************************************************** 267 Chapter 11: Tuning an Oracle Database SQL ID : 1u7rv40zh44sz select * from hr.employees call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.03 0 0 1 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 9 0.00 0.01 6 15 0 107 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 11 0.00 0.04 6 15 1 107 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5 (SYSTEM) Rows Row Source Operation ------- --------------------------------------------------- 107 TABLE ACCESS FULL EMPLOYEES (cr=15 pr=6 pw=6 time=0 us cost=3 size=7276 card=107) Rows Execution Plan ------- --------------------------------------------------- 0 SELECT STATEMENT MODE: ALL_ROWS 107 TABLE ACCESS MODE: ANALYZED (FULL) OF ‘EMPLOYEES’ (TABLE) Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 10 0.00 0.00 SQL*Net message from client 10 24.74 42.68 db file sequential read 1 0.01 0.01 db file scattered read 1 0.00 0.00 ******************************************************************************** The resulting output file shows the following data in chronological order: ✓ Each SQL statement executed ✓ The corresponding SQL execution plan ✓ The performance metrics for each statement You should review the TKPROF output file to find statements that aren’t per- forming well and tune those individual statements. Once all the statements are tuned, execute and trace the statements again to verify they have been improved. 268 Part III: Caring for an Oracle Database Chapter 12 Troubleshooting an Oracle Database In This Chapter ▶ Using troubleshooting methodology ▶ Troubleshooting with Oracle database logs ▶ Employing other diagnostic utilities No matter what the salespeople claim, any system made by mortal beings will have issues and sometimes even break; that’s reality. Worse yet, those same salespeople who claimed their system was perfect aren’t around to fix it when it does break; that’s your job. Fortunately, this chapter provides the information you need. Before jumping into database-specific diagnostic techniques, we give you a method for troubleshooting at the system level. Remember: Oracle exists as part of an overall information system. Here you explore the methods and tools you need to operate at system level. Oracle provides a wealth of information, almost an overload, in its multiple log and trace files. Between the different files and tracing levels, odds are the information you need to solve the problem is there somewhere . . . if you know where to look for it. We provide that info. Just when you thought you couldn’t get any more information about your Oracle database, we do just that via Oracle diagnostic tools and scripts. We’re not showing tools that provide pointless data; we explain tools that provide fast, actionable information. 270 Part III: Caring for an Oracle Database Troubleshooting with System Methodology If an Oracle crash hasn’t happened to you yet, it will happen sometime. And when it does, it won’t be at a convenient time. The problem is that people assume that because they have an Oracle-based system, the problem must be with Oracle. It could be, but you don’t know just yet. Oracle is simply a component of a larger system and the root cause and solution may not be Oracle based. Even if you get an Oracle database error message, the cause may be something outside of Oracle. Don’t react to a problem report on face level. Apply a structured, repeatable pattern when addressing problems. We can’t stress this next statement enough: Yours is a technical profession and you’re paid to solve problems; not simply to react and hope for a quick fix. Everyone has a troubleshooting methodology tailored for their unique envi- ronment, but we suggest the following as a start: 1. Identify the real problem. Determine and confirm what is happening in the system. 2. Perform basic system checks. Check the server, operating environment, and connectivity for outright errors and performance degradation. 3. Perform basic database checks. Confirm the database is running and see if you can log in to it. 4. Determine what your error messages mean. 5. Develop a solution and apply it. Confirm that the fix works and that there aren’t unintended consequences. With experience and time you will modify the steps for your environment. Depending on the situation, you may process some steps very fast — but they’re still processed, not skipped. Identifying the real problem Before doing anything to “fix” the perceived problem, you need to know what the real problem is. You can’t guess or assume. It’s far better to treat the real cause of a problem, not just the symptoms. 271 Chapter 12: Troubleshooting an Oracle Database People reporting problems get excited, miss key details, make assumptions, and often inaccurately state the nature and severity of a problem; that’s simply human nature. If you think otherwise, ask any cop or ER doctor about the quality of the initial witness reports they receive. This is exacerbated in computer work because many people who are reporting problems aren’t technical and cannot articulate very well. You need to determine what system component has the problem and what is specifically happening before you can develop and apply a fix. Ask the follow- ing questions: ✓ What: What specifically is happening? Have the user walk through what he’s doing when the error occurs. Work directly with the person having problems and monitor in real time rather than getting second- or third- hand information. Get screen shots or the error messages themselves. ✓ Who: Who’s being impacted? Is it one or two users or everyone? Is it a specific sub-classification of users or everyone? Also, is it your produc- tion, test, or development system? Never assume that because someone is excited, it must be production. Nothing is more embarrassing then trying to fix the wrong database. ✓ Where: Are affected users spread over a wide geographic location or are affected users in a specific city or building? ✓ When: How long has this been occurring and has it occurred before? Also, does it happen every time or just sometimes? If it only happens occasionally, drill down into what’s being done prior to the error. If it only occurred since a recent system change (such as patch, upgrade, reboot), that can be a valuable clue. The question “What has recently changed in the system” is a great question to ask! ✓ How bad: Is this a total loss of service where the company is stopped or is it just an annoyance on a seldom-used development system? After asking these questions you should know what’s happening, who it’s happening to, how bad it is, and when it started. You should also have a rough idea of what subsystem or components to start checking. Keep a cool head when troubleshooting hot issues; be methodical and work in a logical manner until the problem is fixed (and confirmed to be fixed). Others may become excited, stressed, or unprofessional, but you need to keep your wits and professionalism as you work toward a solution. Don’t let yourself be intimidated by irate users or management standing over your shoulder. 272 Part III: Caring for an Oracle Database Performing basic system checks You need to perform basic system checks to ensure the system is in a state that can support a database. If the network is down, server is overloaded, or disk system has ran out of space, your database may be impacted and dis- play database errors, but the root problem is system related. Investigate these key areas: ✓ Network: Can you connect to the server or application? ✓ Server utilization: What are the top processes on the server? ✓ CPU utilization: Is the CPU maxed out? ✓ Memory: How much memory is available? ✓ Available disk space: Is there disk space available? ✓ System event logs: Is anything being reported to the system? You don’t need to be a system administrator to perform these checks. Network If you can’t connect to the database server, odds are neither can your users. You have two easy ways to check this: ✓ Ping to test server connectivity. ✓ Log in to the server as the Oracle user. From the DOS or Linux command prompt, type ping to see if the target server can be reached. $ ping classroom.perptech.local PING classroom.perptech.local (192.168.2.121) 56(84) bytes of data. 64 bytes from classroom.perptech.local (192.168.2.121): icmp_seq=1 ttl=64 time=0.020 ms 64 bytes from classroom.perptech.local (192.168.2.121): icmp_seq=2 ttl=64 time=0.007 ms 64 bytes from classroom.perptech.local (192.168.2.121): icmp_seq=3 ttl=64 time=0.007 ms --- classroom.perptech.local ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 1999ms rtt min/avg/max/mdev = 0.007/0.011/0.020/0.006 ms 273 Chapter 12: Troubleshooting an Oracle Database In the preceding code three ping packets were sent and all three arrived successfully. Depending on the ping version, you get back slightly different output, but all specify if the server was reachable. If the server comes back as unavailable, the problem is one of these things: ✓ The server is shut down. ✓ The network is down. ✓ You’re prevented from pinging servers. Sometimes security blocks ping, so check if it works before problems occur so you know the test is valid. Once you confirm the server can be reached, try actually logging in as the owner of the Oracle software if possible. Note that on some systems you have to log in as yourself (for security-auditing purposes) and then switch users to the Oracle software owner. This confirms the server is not only running, but can support a login attempt. Server utilization If a program, process, or job is consuming all the resources on a server and has been doing so for a long enough time, a database can ✓ Slow down ✓ Be rendered unusable ✓ Be killed (in rare cases) The processes themselves may be valid, or be a competing database (mul- tiple databases can be on the same server), or an out-of-control, runaway process. To determine the nature of the programs running, you first must identify them before you can determine if they’re valid or hurting the system. There are several graphical tools to do this. ✓ On Windows, use Windows Task Manager to see which applications are running (under the Applications Tab). For more detail use the Processes tab shown in Figure 12-1. ✓ For Linux/UNIX, use the command top to display the top processes on a server, as shown in Figure 12-2. The output is text based and refreshed every few seconds. You can see the most active processes on the server and their process ID (PID). 274 Part III: Caring for an Oracle Database Figure 12-1: Windows Task Manager has multiple processes executing as multiple users via the Processes tab. Figure 12-2: The top utility shows the top processes. 275 Chapter 12: Troubleshooting an Oracle Database Additionally, at the top of the screen is the machine’s load average. This derived value reflects relative load on the server. • Values up to 3 are light and shouldn’t reflect performance problems. • Values in the teens reflect higher use of a busy system and perfor- mance may suffer. • Values above 20 indicate a busy system where performance is likely impacted. ✓ For Linux/UNIX, the uptime command helps you see system load: $ uptime 23:13:03 up 4 days, 10:27, 1 user, load average: 0.00, 0.00, 0.00 System load values are the same as with top: • The leftmost value is the current load. • The middle value is the load 5 minutes previous., • The rightmost value is the load 15 minutes prior. The other useful value is the time since the last server restart. Obviously if users reported problems and you see the server recently rebooted a few minutes prior, the server reboot (or crash) is the likely culprit. ✓ On UNIX Sun Solaris systems, prstat is an alternative to top. ✓ On HP-UX systems, glance is extremely useful. CPU utilization Servers may have single or multiple CPUs. Regardless, there needs to be pro- cessing available for the server to process application requests. If a machine has a very high or complete CPU use, performance issues will occur. ✓ On Windows the previously mentioned Windows Task Manager has a Performance tab. That tab displays CPU use as a percentage and as recent spikes, as you can see in Figure 12-3. ✓ For Linux/UNIX systems, the previously described top command dis- plays CPU utilization at the top of the screen. 276 Part III: Caring for an Oracle Database Figure 12-3: The Windows Task Manager Perfor- mance tab shows CPU use. Memory If the server is lacking memory, system performance suffers or even stands still. It isn’t desirable to run a server with little or no memory available. If you find the server is consistently memory starved, either add more memory or reduce the amount of memory allocated for programs. ✓ To check memory on Windows, the Windows Task Manager Performance tab provides the total memory on the machine and amount available. ✓ Linux/UNIX systems have multiple tools to check memory, but the top utility provides this information rapidly. Available disk space Disk space is different than disk utilization. The frequency of reads and writes on a disk is utilization and can be a major performance factor. Running out of available disk space can bring your system to a halt and is the focus here because you, as the DBA, can do something about it. However, poor disk utilization won’t often bring your system to a complete standstill without warning. Measuring and accurately interpreting disk utiliza- tion, especially in large SAN environments, is outside the scope of this book. You should work with your storage engineers to address that topic. What can happen when a disk fills up? It depends on what’s writing to that disk. At minimum, log files can’t be written to and tablespaces can’t be expanded. At worst, archive log files can’t be successfully written and the 277 Chapter 12: Troubleshooting an Oracle Database database hangs. With other software, processes can spin high amounts of CPU and Java Virtual Machines can crash — any of which is likely to generate a panicked call to your desk. The quickest way to check for disk space is to see if any file systems are 100 percent full. ✓ For Windows systems, the fastest way is to go to My Computer and look at free space for each disk drive. Be sure to have Details selected under the View tab to get the full information. ✓ The df -m command helps Linux users: $ df -m Filesystem 1M-blocks Used Available Use% Mounted on /dev/md4 179203 21288 148665 13% / /dev/md0 213 17 186 9% /boot tmpfs 943 0 943 0% /dev/shm /dev/md2 10653 503 9601 5% /tmp /dev/md3 11626 819 10207 8% /var This code shows the file systems, their percentage used, percentage free (available), and the actual amounts in megabytes. The df -k command can show the same info but listed in kilobytes. This is useful because some versions of UNIX don’t support the -m flag. ✓ On HP-UX UNIX systems, use bdf. System event logs If all else fails, listen to what the computer is telling you, so to speak! As a DBA, you should have at least read access to the system event logs on your server and hopefully all servers that are part of the application. System event logs record routine events on the server, but also may list special error events that could be the cause of your system problems. Sometimes it clearly lists hardware issues, or it could be file systems are full, or maybe listing that the machine just rebooted or crashed. All of these are good things to know when you’re trying to track down a problem. The location of the event logs can be varied and often additional logs are beyond the OS logs to review once you learn your system. ✓ On Windows systems go to Control Panel➪Administrative Tools➪Event Viewer to see the system and application logs. ✓ On Linux/UNIX systems, /var/adm/messages and /var/log/syslog are quite valuable. The dmesg command can see the end of the most recent system log file. Much of this information may not make sense to a DBA who isn’t OS savvy; however, seeing errors can be enough to seek the opinion of the system administrator. 278 Part III: Caring for an Oracle Database Performing basic database checks If you’ve confirmed you can get to the server and that it should be able to support an application database, perform three basic database checks: ✓ Verify the database is running. ✓ Verify Oracle Net functionality. ✓ Perform a database connection. Running database instance See if it’s actually running. Oracle database instances execute with different mandatory processes such as PMON. ✓ On Linux/UNIX systems, simply check for the PMON process. Without PMON there’s no Oracle database instance running. $ ps -ef|grep pmon oracle 13515 1 0 23:24 ? 00:00:00 ora_pmon_dev11g The PMON process is for dev11g, which is a running Oracle database. You could search for additional database processes, but if you know PMON is, you can safely assume the rest of the database instance is running too. ✓ On Windows systems check Control Panel➪Administrative Tools➪ Services to see if the Oracle service has started. You can also look under Windows Task Manager to find similar information. After you confirm a working basic network infrastructure and a connectable database server, you have to confirm the Oracle Net infrastructure is working so users can connect to the database. Moonlighting Ever notice the system time examples in many technical books are often late at night or very early in the morning, like the 11:13 p.m. exam- ple regarding the uptime command? Many, if not most, technical authors are primarily consultants or otherwise actively working in their field full time. Benefit to the reader is you get good, practical, and current information. Negative for the writers is they don’t get a lot of sleep during these projects! 279 Chapter 12: Troubleshooting an Oracle Database Oracle NET functionality Execute tnsping from the DOS or Linux command prompt. It uses the Oracle NET protocol to see if it can connect to the database. $ tnsping dev11g TNS Ping Utility for Linux: Version 11.1.0.6.0 – Production on 17-SEP-2008 23:30:27 Copyright (c) 1997, 2007, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/11.1.0/db_1/network/admin/sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION_LIST = (DESCRIPTION= (ADDRESS_LIST= (ADDRESS= (PROTOCOL=tcp) (HOST= classroom.perptech.local) (PORT=1521))))) OK (0 msec) Note how it specifies the host, port, SID information for that database. ✓ If that doesn’t match what you know to be correct, it is a clue. ✓ If it doesn’t come back at all, it may be a network or server failure. ✓ Depending on the Oracle error returned, it may suggest an error with the database listener process. Database connection When you know the database is up and you can establish an Oracle Net com- munications handshake, log in to see if you can establish a database session. 1. Identify the problem tier that users are reporting. • In a client-server application, this is your workstation. • In a multi-tier architecture, this is likely the web application server. 2. From that tier, try logging into the database via SQL*Plus, preferably as a typical user: $ sqlplus system@dev11g SQL*Plus: Release 11.1.0.6.0 - Production on Sat Sep 20 12:59:03 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved. Enter password: 280 Part III: Caring for an Oracle Database Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> show user USER is “SYSTEM” The SQL*Plus attempt shows connecting to a remote database as an applica- tion user. You want to force the use of the Oracle Net infrastructure in this test. The @dev11g denotes that you’ll use Oracle Net to connect to the remote data- base rather than directly logging in if you’re already on the same server. If you logged in, then you’re done with your basic database checks; you con- firmed a user can connect to the database. On the other hand, you may have encountered any of the following common errors: ✓ Cannot archive log file: If the archive dump destination is full, or for any other reason the archiver processes can’t properly write the archive log file, your login attempt will fail. Oracle does this because even a login generates archive log information and Oracle guarantees it will track that information or it won’t perform the action. Fix: Resolve that archiver problem. You can always log in on the server itself with / as sysdba to perform maintenance. ✓ Database in restricted session: The database may be running, but if in restricted session only users with RESTRICTED SESSION system privi- lege can login. Generally, the database is in the state because some form of database maintenance is occurring and the DBA doesn’t want normal users in the system. Fix: Determine why the database is in restricted session mode and take it out of that mode if appropriate. Or you can grant RESTRICTED SESSION to the user(s), but that usually defeats the purpose of having restricted session. ✓ Login simply hangs: Sometimes the login attempt hangs and doesn’t immediately generate an error message. These can be tough to diagnose because you’re not getting any feedback. Fix: Try connecting from a different tier. Also try logging in from the data- base server itself; see if you can find where you can connect from and gen- erate an actionable log message. Also revalidate your network, server, and system checks to confirm they are valid, and search for error messages. Performing basic database checks is a way to confirm there’s nothing obviously wrong with the database, such as it isn’t running or you can’t connect to it. Once you perform those checks, you can begin the more detailed problem and error log analysis. 281 Chapter 12: Troubleshooting an Oracle Database Analyzing error messages Ever hear the expression “hiding in plain sight”? That often happens when people see an Oracle error message. They see it, but they don’t actually read it and think about what it is saying. As a result, the most valuable clue you have isn’t being fully maximized. Avoid falling into that trap. Make the most of your error messages: ✓ Slow down and read the error message — several times if necessary. Think about what it is saying. Don’t just rattle off ORA-1234 and the description. Ask yourself what specific action is failing based on the context of the error message and what is going on at the time of the message. ✓ Pretend you’re the application and ask what you’re doing when the error occurred. Then apply the text of the message to see which piece or action is failing. ✓ Apply most of your focus on the first error message you receive. Often a series of error messages will occur related to one event, but typically that first message is the cause of the other messages. ✓ Know the different types of error messages and which components they relate to. • ORA denotes database or SQL errors. • TNS denotes database listener or Oracle Net communication issues. • HTTP is web related. • LDAP denotes details with your directory server, perhaps Oracle Internet Directory. The architecture of your system will determine what components may generate errors. Know what components exist within the system and the process flow so you can tell what part of the system is failing based on the type of message. ✓ Become familiar with normal messages versus extraordinary error mes- sages. Many harmless informational messages crop up for events that aren’t errors — particularly when working with log files. Know what your system logs look like during normal operations so that when real errors do occur, you can identify them easily in a myriad of informa- tional messages. ✓ Plug the error message into Oracle Metalink and Internet search utili- ties to get more detailed descriptions and possible fixes. Expect lots of irrelevant information and false leads. But odds are your search will also include information that helps identify and fix the problem. 282 Part III: Caring for an Oracle Database Knowing database and system anatomy A firm understanding of Oracle database architecture and processes is key to your ability to understand error messages and diagnostic output. Think of it as database anatomy. Just as you would flee if your doctor said “I don’t really understand that heart-stuff”; what kind of DBA is clueless about the SYSTEM tablespace? Even if you think you know it, a periodic review of Chapter 2 is time well spent for any DBA. Where in the overall system does your database fit and what are the compo- nents? If people are reporting an HTTP-404 error, you probably want to get the web administrator involved as it may be a web server or content prob- lem. But if your database generates the HTML content via mod_plsql Web Toolkit, it may actually be your database having issues. Not knowing that would result in the problem being routed to the wrong people, further delay- ing the fix. There simply is no substitute for knowing the specifics of how your system works and being able to apply that knowledge. Error system example Look at this example of a common message that confuses people. Upon analysis the cause is simple to identify. ORA-01034: ORACLE not available. ORA denotes a database message (versus TNS for a listener or HTTP for a web error). What does Instance not available mean in terms of databases? If you know database architecture, you know that an instance is the memory and background processes for a database. Thus, the database instance may not be running; you need to confirm that. A quick ps –ef | grep pmon on the server shows no PMON process running, so now you have confirmed the database instance is down. A further check using the uptime command shows the server was restarted 15 minutes ago; you can assume the database didn’t restart after a server crash or reboot. At this point you can check database logs to see if the instance tried to restart and failed or no attempt was made to restart. Based on that, you can manu- ally restart the database and get users back to work. oerr utility The oerr utility gets more information about an error message. This com- mand-line utility is where you specify an error number and a problem cause and possible solution is provided. While not in-depth troubleshooting, it is very handy: 283 Chapter 12: Troubleshooting an Oracle Database $ oerr ora 1034 01034, 00000, “ORACLE not available” // *Cause: Oracle was not started up. Possible causes include the following: // - The SGA requires more space than was allocated for it. // - The operating-system variable pointing to the instance is // improperly defined. // *Action: Refer to accompanying messages for possible causes and correct // the problem mentioned in the other messages. // If Oracle has been initialized, then on some operating systems, // verify that Oracle was linked correctly. See the platform // specific Oracle documentation. Developing and applying a solution How do you fix a problem? Sometimes it is a simple command that is obvi- ous even to the most inexperienced administrator. More commonly it is a multi-step operation that may span both database and non-database areas. Consider these guidelines as you develop and implement your plan. Clearly for very simple and obvious fixes, you are not going to apply every step listed in the following exhaustive detail. However, you should review the guidelines and see how they apply to what you are doing. Technical fixes and software patches do not always work, which is outside your control. However, planning the repair process is something you can con- trol and will greatly better the odds of your success. Researching You should understand what is happening and why. What is causing the prob- lem and how is that best remedied? ✓ Review the error messages. ✓ Read the documentation. ✓ Search the Internet. ✓ Talk to other administrators. ✓ Get Oracle Support assistance. It’s dangerous to apply a fix when you don’t know why something is occurring. Only through understanding will you have the confidence that whatever fix you apply is the right one and won’t cause further damage. 284 Part III: Caring for an Oracle Database Develop the pseudo-code list of steps that you will need to perform based on your research. This may cause more questions as it is developed, but that is good. The end product is a high-level plan of how to fix the problem. Planning How will you specifically fix the problem? Once equipped with your high-level plan, make it technically detailed. ✓ Identify the technical substeps for each high-level pseudo-code step. ✓ Know what commands need to be issued and by which account. ✓ Know the time necessary for each step to occur and dependencies between steps. ✓ If additional software or patches are required, make sure those needs are addressed. Have another administrator review your fix-planning steps to make sure you haven’t skipped anything. Ramifications If you perform the fix, what are the side effects? ✓ Will you have to restart and place the system in restricted session for a complex fix, kicking off system users? ✓ How long will the system be unavailable? ✓ When is the best downtime? ✓ Can you perform the fix solo, from end to end, or do you need help from other groups (such as networking or the system administrator)? ✓ Does the fix void your software warranty or break other components? Coordinating with other groups and the user community for a fix is often a big hurdle when working on large, distributed, and complex systems. It’s helpful to have management support as well as documented policies and procedures to support coordination efforts. Testing Don’t tell me you’re trying something in production before testing it first! If at all possible, re-create the problem in a test environment and apply the fix there before doing it in production. Testing does these things: ✓ Ensures your steps are complete ✓ Provides accurate timeframes for the total fix 285 Chapter 12: Troubleshooting an Oracle Database ✓ Verifies your syntax with the opportunity to make mistakes ✓ Confirms the problem is actually fixed ✓ Verifies there are no unintended consequences Many organizations are under mandate to test changes before going into pro- duction, and that is generally a good policy. With troubleshooting complex problems or operating on large amounts of data, it is even more important. We’ve seen many ill-advised attempts at fixing something without it being tested, only to end in disastrous results. Don’t let that happen to you. Fallback options The fix doesn’t work and things go from bad to worse. You do have a fallback plan, right? A good administrator always has a workable fallback plan for when things go wrong. Those who don’t sooner or later end up seeking other employment opportunities. Before performing nearly any technical fix, do these things: ✓ Take another database backup or verify your most recent backups are valid and accessible. ✓ If backups are stored off-site for disaster recovery, recall those backups. You may need them before you start your maintenance operation. ✓ Consider taking multiple backup copies too, in case one copy is bad. Parachutists jump with a backup chute; shouldn’t you? Once large amounts of data have been modified, can it be undone without a backup? You may need to work with the application developers on data changes. Also consider other items that need to be undone outside the data- base. For example, a network change with DNS may take several hours to take effect. If you push a change to thousands of client workstations, how do you roll that back if necessary? Support Odds are you will be performing your maintenance over a weekend or late at night. If so, are the other people available and accessible to perform their parts of the fix? ✓ Do you have everyone’s phone numbers? ✓ Are they willing and able to help you at 3 a.m. when you discover a problem? ✓ Are they authorized to make the change? 286 Part III: Caring for an Oracle Database Verification Who is going to test and confirm the fix actually worked? A test plan with tes- ters or knowledgeable users is a good idea, particularly if data or application changes are necessary. ✓ Run through the plan first; otherwise you may discover broken parts of the application unrelated to the problem you are attempting to fix. ✓ Make sure these testers are available once you are done with your work. Once you have developed, tested, applied, and verified your technical fix, what’s the final step before turning it over to the users? Often, a full database or system backup. The benefit is that if something unrelated occurs and you need to restore, you don’t need to go through the previous fix. Troubleshooting Using Oracle Database Logs You need to dive into the Oracle logs themselves. Each database has a set of directories where key log, trace, and dump files are stored. Database log infrastructure In versions of Oracle prior to 11, all logs were simply under several ORACLE_ BASE/admin/ subdirectories. These were flat files dumped into audit, background, or user dump subdirectories and it was up to the DBA to manage them. This was okay, but left room for some improvement. Starting in Oracle 11, log file structure and management is modernized and referred to as the Automatic Diagnostic Repository (ADR). The file structure is slightly different than previous versions, but ADR promises the following: ✓ Integrated log management not just for the database but other Oracle products. Currently, Automatic Storage Management and listener will also write to the new log infrastructure. ✓ Event logging in terms of incidents with included diagnostic data and stored in zip files that can be reviewed and sent to Oracle support. The idea is to better compartmentalize error events and neatly package them so they can be sent directly to Oracle support. ✓ Incident Flood Control to intelligently limit the creation and size of trace files. If an event repeats at an extreme rate above a defined threshold, only the occurrence of the event is logged. 287 Chapter 12: Troubleshooting an Oracle Database It is important to know where the key diagnostic files are located: ✓ The location for the diagnostic subdirectories (diag) is the ADR_BASE and is typically under the ORACLE_BASE. ✓ The location of the base for the log subdirectories is the ADR_HOME and is defined by database parameter DIAGNOSTIC_DEST. ✓ The ADR_HOME is beneath the ADR_BASE location and is under the database SID directory. The structure for ADR_HOME for databases follows: $ADR_BASE/diag/rdbms// For example, here’s the following structure for the devg11 database: $ ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g alert cdump hm incident incpkg ir lck metadata stage sweep trace The ADR_HOME location is the full path up to and including the second refer- ence to devg11. You see this same information neatly stored within the database and can be queried via V$DIAG_INFO: SYS@dev11g>select name, value from v$diag_info; NAME VALUE ----------------------- ------------------------------------- Diag Enabled TRUE ADR Base /u01/app/oracle ADR Home /u01/app/oracle/diag/rdbms/dev11g/dev11g Diag Trace /u01/app/oracle/diag/rdbms/dev11g/dev11g/trace Diag Alert /u01/app/oracle/diag/rdbms/dev11g/dev11g/alert Diag Incident /u01/app/oracle/diag/rdbms/dev11g/dev11g/incident Diag Cdump /u01/app/oracle/diag/rdbms/dev11g/dev11g/cdump Health Monitor /u01/app/oracle/diag/rdbms/dev11g/dev11g/hm Default Trace File /u01/app/oracle/diag/rdbms/dev11g/dev11g/trace/dev11g_ora_2942.trc Active Problem Count 3 Active Incident Count 5 11 rows selected. SYS@dev11g> Within each database directory are subdirectories where different files are stored. Table 12-1 lists each primary directory and its purpose. 288 Part III: Caring for an Oracle Database Table 12-1 Database Trace and Log Directories Directory Purpose alert Stores very important XML-formatted alert log for database. cdump Core dump location of memory stack when a process fails. incident Subdirectories relating to individual events or incidents. trace Trace and dump files for background and user processes. Also contains text formatted alert log. This is a listing of each directory: $ ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g/alert log.xml $ ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g/cdump ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g/incident incdir_52994 incdir_52995 incdir_53178 $ ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g/trace alert_dev11g.log ashrpt.txt dev11g_m000_13544.trc dev11g_m000_13544.trm tk_trace.txt These directories can get cluttered with many files and eat up disk space. Have a process to clean up the trace, cdump, and incident directories. Database alert log By far the most important file to review for a database is the alert log. This file is where database-level errors are written and operations such as startup, shutdown, and other events are logged. Oracle writes to this text-based file in a chronological order when the database is running. The alert log is in the alert subdirectory and is named log.xml. ✓ Whenever a problem occurs, review the alert log file. ✓ Review the alert log file daily (if you’re the DBA) to ensure errors are not occurring undetected. Many DBAs even write scripts to scan the alert log for errors and have email messages sent to them if key events are detected. Also, many DBAs copy off their alert log weekly to prevent it from becoming excessively large. Prior to Oracle 11g, the alert log was a text-formatted file. With 11g onwards, it is XML based, which allows easier viewing with web-based tools. 289 Chapter 12: Troubleshooting an Oracle Database Here’s a sample of an alert log file in XML format: Starting up ORACLE RDBMS Version: 11.1.0.6.0. Using parameter settings in client-side pfile /u01/app/oracle/admin/dev11g/pfile/init.ora on machine classroom.perptech.local System parameters with non-default values: This code shows routine database messages for a database startup. A text-formatted version is still available for people using command-line editors like vi or Notepad. It is in the trace subdirectory and has the standard name format alert_.log (which is alert_dev11g.log in this example). Without the XML tags you can easily read it via a command-line utility. Here’s the same information as the XML file, but without the tags: Wed Apr 16 10:55:57 2008 Starting ORACLE instance (normal) LICENSE_MAX_SESSION = 0 LICENSE_SESSIONS_WARNING = 0 Shared memory segment for instance monitoring created Picked latch-free SCN scheme 3 Using LOG_ARCHIVE_DEST_1 parameter default value as /u01/app/oracle/product/11.1.0/db_1/dbs/arch Using LOG_ARCHIVE_DEST_10 parameter default value as USE_DB_RECOVERY_FILE_DEST Autotune of undo retention is turned on. IMODE=BR ILAT =18 LICENSE_MAX_USERS = 0 SYS auditing is disabled Starting up ORACLE RDBMS Version: 11.1.0.6.0. Using parameter settings in client-side pfile /u01/app/oracle/admin/dev11g/pfile/init.ora on machine classroom.perptech.local System parameters with non-default values: 290 Part III: Caring for an Oracle Database Here’s what an Oracle error looks like: ORA-279 signalled during: alter database recover logfile ‘/u01/app/oracle/flash_recovery_area /DEV11G/archivelog/2008_09_09/o1_mf_1_59_4df4td9j_.arc’... Review and manage the alert log regularly. Trace and dump files When a problem event occurs (such as a failed process or failed memory allocation), log files for that event are written into the trace directory. The format for the log file name is __.trc: $ ls $ORACLE_BASE/diag/rdbms/dev11g/dev11g/trace dev11g_m000_13544.trc dev11g_m000_13544.trm tk_trace.txt Here are the contents of a trace file: Trace file /u01/app/oracle/diag/rdbms/dev11g/dev11g/trace/dev11g_m000_13544.trc Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options ORACLE_HOME = /u01/app/oracle/product/11.1.0/db_1 System name: Linux Node name: classroom.perptech.local Release: 2.6.18-53.1.14.el5 Version: #1 SMP Wed Mar 5 11:37:38 EST 2008 Machine: x86_64 Instance name: dev11g Redo thread mounted by this instance: 1 Oracle process number: 30 Unix process pid: 13544, image: oracle@classroom.perptech.local (m000) *** 2008-08-27 16:01:46.547 *** SESSION ID:(118.2743) 2008-08-27 16:01:46.547 *** CLIENT ID:() 2008-08-27 16:01:46.547 *** SERVICE NAME:(SYS$BACKGROUND) 2008-08-27 16:01:46.547 *** MODULE NAME:(MMON_SLAVE) 2008-08-27 16:01:46.547 *** ACTION NAME:(JAVAVM JIT slave action) 2008-08-27 16:01:46.547 joxjitexe exiting 291 Chapter 12: Troubleshooting an Oracle Database The difference between a dump and a trace file: A trace is an ongoing log of a problem event. The dump is the one-time dumping of information into a file for a problem event. As a DBA you should review these text files to diagnose what is occurring. If a process crashes, a core dump can be created in the cdump directory. This is a binary trace file of the memory process and its contents at the time of the crash. Although many people consider these “hands-off” for a DBA to review, that isn’t necessarily the case. The Linux and UNIX strings command can show the printable text of a binary file. If you opt to upload the core file to any support organization, you may want to review it first for username and pass- word combinations as they are sometimes present in clear text in these files. Listener log You may have to track connections into the database via the listener. Every time a connection to the database occurs, that event (or failure) is stored in the listener log. Chapter 5 goes into greater detail of the database listener architecture. Knowing where listener logs are generated is important to troubleshooting. You can find the listener log under the ADR_BASE/diag/ tnslsnr directory tree. (In this example it’s /u01/app/oracle/diag/tnslsnr/classroom/listener/trace/ listener.log.) Here’s a sample log entry: 21-SEP-2008 23:59:44 * (CONNECT_DATA= (CID=(PROGRAM=) (HOST=classroom.perptech.local) (USER=oracle))(COMMAND=status) (ARGUMENTS=64) (SERVICE=(ADDRESS=(PROTOCOL=TCP) (HOST=classroom.perptech.local) (PORT=1521))) (VERSION=185599488)) * status * 0 Key information is the time, host, and program for the incoming connections. Here’s a Quest TOAD (see Chapter 7) utility user connecting, most likely from her workstation: 05-MAY-2008 11:57:45 * (CONNECT_DATA= (SERVICE_NAME=192.168.2.121) (CID=(PROGRAM=C:\Program?Files\Quest?Software\TOAD\TOAD.exe) (HOST=LPT-MPYLE)(USER=mpyle))) * (ADDRESS=(PROTOCOL=tcp) (HOST=192.168.2.170) (PORT=3108)) * establish * 192.168.2.121 * 12514 292 Part III: Caring for an Oracle Database Finally, an error is occurring: TNS-12514: TNS:listener does not currently know of service requested in connect descriptor You can search for the Transport Network Substrate (TNS) error code in the lis- tener log to see what errors are occurring. This is useful as there will (hope- fully) be far more connections than errors and, like the alert logs, the listener log can grow large. Benefiting from Other Diagnostic Utilities As a DBA you should be grounded in the fundamentals of how your database works and where files are located. Sometimes you’ll have only a command-line interface into your database server and have to manually review log files. However, you also should know several easier, faster methods: ✓ Oracle Enterprise Manager ✓ Remote Diagnostic Assistant (RDA) ✓ Database diagnostic scripts Oracle Enterprise Manager Oracle Enterprise Manager (EM) lets you review alert messages on the data- base home page. This easy method of checking for critical errors lets you avoid manually sifting through text files. Figure 12-4 shows the alert messages for dev11g under the section Alerts. You can see multiple error and diagnostic messages and the time they occurred. Clicking the message text itself provides additional information. From within Enterprise Manager, you can enter the Enterprise Manager Support Workbench. Within that tool you can generate the collection of addi- tional diagnostic information with the intent of uploading it to Oracle Support as a Service Request (SR). In Figure 12-5 you can see each error that has occurred and the number of incidents for that error. 293 Chapter 12: Troubleshooting an Oracle Database Figure 12-4: Viewing a database alert message. Figure 12-5: Checking out the Enterprise Manager Support Workbench. 294 Part III: Caring for an Oracle Database Obviously you need to have an Oracle Support account and Customer Support Identifier to submit a package as an SR. This is a good way to streamline and automate your interaction with Oracle Support, which should allow for an easier troubleshooting process. One benefit of formatting the alert log in XML is that you can easily view it via Enterprise Manager. The complete contents of the log and specific error mes- sages can be displayed with timestamp ranges. You can see the most recent 100 entries in Figure 12-6. You see the same information as in the alert log files via manual utilities, but the information is more cleanly presented via Enterprise Manager. It is the graphical representation provided by Enterprise Manager coupled with an intuitive interface and wizards that make EM a useful tool for the DBA. Remote Diagnostic Agent Oracle Remote Diagnostic Agent (RDA) is an Oracle support utility that cap- tures Oracle-related information on an entire server and stores the results in a series of HTML files. Figure 12-6: Viewing alert log contents. 295 Chapter 12: Troubleshooting an Oracle Database The intent is to capture data about the operating system, hardware, Oracle software versions, database instances, listeners, and activities within the database in an automated manner. You can view that information as a series of static HTML pages to get fast graphical access to all Oracle-related infor- mation for a given server. Not only is graphical information useful to DBAs, but when you provide an RDA to Oracle support it gives an accurate picture of your database environ- ment. In fact, one of the first things many Oracle support analysts request is an RDA of your server. Oracle RDA comes as a tar or zip file available for download via the Oracle Metalink support network. Once downloaded, it executes on the server as a Perl script. The output is a zip file that you can ✓ Upload to Oracle support ✓ Unzip into a series of HTML files that you can navigate to find key information In Figure 12-7 you see the main index page of the RDA output where you can drill down into multiple useful areas. Figure 12-7: The RDA main index page. 296 Part III: Caring for an Oracle Database RDAs are a great way to get a quick snapshot of a system even when there are no problems (per se). For example, if you are consulting and need a quick overview of a client’s system, the RDA is very handy. Or if you are taking over an existing database server, the RDA will tell you exactly what is on that server and how it is configured. Diagnostic database scripts Most old-school DBAs from the Oracle 7 days lived and died by their toolbox of database scripts, and for good reason. Database scripts based on internal database views and tables provided the raw information for what is going on in a database. That raw data, coupled with a real understanding of how the database and application worked, often made for a very skilled administrator who could solve most problems. Towards that end, entire books are dedi- cated to database scripts, as well as many web sites with scripts available for download. Oracle provides a set of database scripts in every $ORACLE_HOME/rdbms/ admin directory. In it are core scripts necessary to create a database, build the data dictionary, and other maintenance operations which aren’t very useful for troubleshooting. However, the $ORACLE_HOME/rdbms/admin directory also has useful scripts such as utllockt.sql and utlrp.sql. Use them to search for database locks and compile invalid database objects. We encourage you to become familiar with the scripts in this directory and identify the ones that fit into your toolbox. Many good third-party scripts exist both from books and Internet downloads. We can’t validate everything out there, so use your own best judgment and don’t run anything you don’t understand or trust. However, there are some good scripts available so don’t be afraid to seek out good sources and test them first on your development database. And if all else fails, write your own. Here is one of our favorites we’ve used many times to see what is happening on a database and who is doing it: SYS@dev11g>get show_session_short.sql 1 set linesize 180 2 set pagesize 20 3 col “Logon Time” format a11 4 col “UNIX Proc” format a9 5 col username format a15 6 col osuser format a13 7 col “Program Running” format a20 8 col sid format 9999 297 Chapter 12: Troubleshooting an Oracle Database 9 col “Connect Type” format a12 10 col serial# format 9999999 11 select s.username, osuser, status, 12 to_char(logon_time,’fmHH:MI:SS AM’) as “Logon Time”, 13 sid, s.serial#, p.spid as “UNIX Proc” 14 from v$session s, v$process p 15 where s.paddr = p.addr 16 and s.username is not null 17* order by status, s.username, logon_time SYS@dev11g>@show_session_short USERNAME OSUSER STATUS Logon Time SID SERIAL# UNIX Proc --------------- ------------- -------- ----------- ----- -------- --------- DBSNMP oracle ACTIVE 11:39:11 PM 125 12 29062 SYS oracle ACTIVE 12:18:25 AM 119 829 31376 SYSMAN oracle ACTIVE 11:40:39 PM 124 54 29264 SYSMAN oracle ACTIVE 11:41:19 PM 138 35 29359 DBSNMP oracle INACTIVE 11:37:51 PM 135 13 28749 SYSMAN oracle INACTIVE 11:40:26 PM 129 24 29258 SYSMAN oracle INACTIVE 11:40:49 PM 155 32 29273 SYSMAN oracle INACTIVE 11:40:59 PM 126 54 29275 SYSMAN oracle INACTIVE 11:41:29 PM 132 19 29357 SYSMAN oracle INACTIVE 11:41:39 PM 131 55 29355 SYSMAN oracle INACTIVE 11:41:49 PM 127 323 29361 11 rows selected. SYS@dev11g> While the script is useful, the actual point is to show you the power of a simple script and what it can quickly provide. Despite all the wiz-bang GUI tools and wonderful database advisors, many folks still use database scripts for some, if not all, of their administrative work. A toolbox of useful scripts coupled with modern Enterprise Manager tools provide DBAs with the best capability to manage their databases. 298 Part III: Caring for an Oracle Database Chapter 13 Monitoring and Managing with Enterprise Manager In This Chapter ▶ Working with Enterprise Manager Database Control ▶ Managing users ▶ Metering and Policy ▶ Setting up notifications Whether you began by reading this chapter or started with Chapter 1, you probably know lots of ways to manage your Oracle database. This book offers a few ideas. You may have been approached by various soft- ware companies with their own solutions. The most popular database man- agement approaches follow: ✓ Pure command line with SQL and OS commands ✓ Oracle Enterprise Manager (Database Control/Grid Control) ✓ Third-party software vendor tools ✓ Any combination of these What works best for you? Whatever you’re most comfortable with. Some methods are better than others for specific tasks. Most people end up with some sort of hybrid approach. This chapter focuses on the Oracle Enterprise Manager method. This chapter gives an overview of the tool’s unique features, as well as some navigation through many of its management pages. 300 Part III: Caring for an Oracle Database Tasting Oracle Enterprise Manager Flavors Oracle Enterprise Manager first became available way back in Oracle 7. It has gone through numerous changes since then. Without boring you with too much history, basically it started off as a desktop client and evolved into the web-based application it is today. Oracle supports several current flavors of Enterprise Manager. It’s important to know the differences between these tools. From now on, we refer to Oracle Enterprise Manager as OEM. OEM Java Console The Java-console version of OEM has been available from Oracle 8i through 10g. In 8i and 9i, it served as the main OEM management system. Not only was it a tool for simple management tasks, it connected to a central repository run- ning on a remote central server, which expanded its capabilities to job sched- uling and monitoring and paging. As of Oracle 10g, OEM only shipped as the client version; there’s no connec- tivity to a centralized server. It still has many useful features, though. For quick, GUI-based tasks, you can install and run it on almost any OS with a supported Java Virtual Machine. It doesn’t require a centralized management system. It offers all the basic features for managing the day-to-day operations of the database, such as the following: ✓ Tablespace/data file management ✓ Users/roles/privileges ✓ Startups/shutdowns ✓ Memory management ✓ Initialization parameters On the other hand, and among other advanced features, it can’t work with these: ✓ Scheduler ✓ Jobs ✓ Notifications ✓ Backups 301 Chapter 13: Monitoring and Managing with Enterprise Manager ✓ Data Pump ✓ Data Guard It’s a nice tool for backup and quick-and-dirty operations when you don’t know SQL. But better versions of OEM can suit your needs. The authors of this book were unable to find any information for or against using the 10g Java Console to manage an Oracle 11g database. We did some testing and it functioned quite well. However, keep in mind that the Java Console didn’t ship with 11g. It was deprecated by Oracle for future releases starting with 11g. We recommend using either Database Control or Grid Control if you’re manag- ing an 11g database. OEM Database Control OEM Database Control started shipping in Oracle 10g and above and serves as the junior replacement for the Java Console version that last shipped with 10g. It’s the first major shift in graphical-based management options that Oracle has offered since Oracle 8i. This is a web-based platform. All the commands you can type using SQL are translated into a graphical, point-and-click interface. Some users find this easier than learning and typing SQL commands. Database Control even sup- ports clustering and RAC database management. You must run a Database Control instance for each database you have. You have to start a Database Control stack for each database you want to manage. If you have many databases, you might find this method tedious and resource consuming. Grid Control steps in here. OEM Grid Control OEM Grid Control offers everything in Database Control and much more. The interface is similar when working on individual databases, it also acts as a central console for managing your entire environment: ✓ Oracle Software stacks ✓ Windows and Linux operating systems ✓ Microsoft SQL Server ✓ Other software products 302 Part III: Caring for an Oracle Database With regard to databases, it can register and maintain Oracle versions from 8iR3 through 11gR1. As of this writing, Oracle hasn’t shipped 11g Grid Control. However, they provided a patchset (10gR4) for 10g that certifies it for 11g database installations. Since 11g Grid Control has yet to ship, this chapter focuses on working with 11g Database Control. Grid Control is installed on its own centralized server in your enterprise. Then you deploy the Oracle Management Agent to all the hosts which soft- ware you want Grid Control to manage. The install and setup can be a little intimidating at first, but if you have a diverse environment with many servers and versions of Oracle, it can be a lifesaver in the long run. Configuring Enterprise Manager with the DBCA The easiest way to set up database control is to configure it during database creation with the Database Configuration Assistant (DBCA). Chapter 4 briefly describes this option. Figure 13-1 shows where the DBCA asks if you want to configure your database with Database Control (for local management). We recommend Database Control because it is the easiest approach. When you let the DBCA set up the database for you, it gathers the required answers for the installation while it takes you through different steps. Once your database creation is complete, open a browser and log into Database Control to begin managing your database. Typically, this URL is most common: https://:1158/em/console. Figure 13-1: The Database Configur- ation Assistant offers its Enterprise Manager Options screen. 303 Chapter 13: Monitoring and Managing with Enterprise Manager You can log in with any username that has database administrator (DBA) privi- leges. SYSMAN is the default user who owns the repository. You choose the password while you’re making the database. Also, use the SYSDBA option if you want to do advanced DBA activities like backups or starts and stops. Just make sure your user has the SYSDBA privilege. Creating and Managing Database Control Users When you first create your database, three users are allowed to log in: ✓ SYS ✓ SYSTEM ✓ SYSMAN However, creating your own users is best practice. This way each person can set up her own tasks and notifications and it’s easier to identify who has made changes. In Enterprise Manager Database Control, all users are super users. This means that they can do almost anything in the tool. Follow these steps to create a user: 1. Click Setup in the upper-right corner of any page within Enterprise Manager. 2. Click the Administrators link (on the left). Figure 13-2 shows the link, which takes you to a list of users who are allowed to log into Database Control. You also see a Create button on top of that list. 3. Click the Create button. You see four fields. 4. Fill in these fields: • Username • Password • Confirm password • Email address You also see a flashlight icon next to the username. With it you can choose an existing user to assign Database Control privileges. 304 Part III: Caring for an Oracle Database Figure 13-2: Database Control Configur- ation Page. 5. Click the Review button on the bottom of the page. Figure 13-3 shows an example of what you might see. 6. Click the Finish button to complete the task. Removing users is simple. Click Setup in the upper-right corner of any page and then follow the Administrators link in the left sidebar. After that, click the radio button next to the username and then click the delete button on top of the user list. Figure 13-3: Review the user you’re creating in Enterprise Manager Database Control. When you remove a user via the Administrators page, the user is also removed from the database. So, if you created a Database Control user by choosing an already existing user, when they are removed from Database Control, they are gone for good from Database Control and the database. 305 Chapter 13: Monitoring and Managing with Enterprise Manager Working with Metrics and Policies One of Database Control’s best features is automatic monitoring of your database with metrics and policies. This is a key component of your DBA job. Database Control uses metrics and policies to save you from having to write all kinds of programs by hand. Metrics and policies are ways of monitoring in the system. ✓ Metric: A measurable point of data about the current operating data- base; typically associated with performance or availability. For example, you might want to know when free space drops below a certain point in your tablespaces or if the CPU exceeds 90 percent usage. ✓ Policy: A particular condition that users mustn’t violate; typically asso- ciated with security. For example, you might want to know if someone logs into the database as SYSDBA or gains unauthorized access to cer- tain features. ✓ Target: A component of the Oracle installation that Enterprise Manager can manage and monitor. Targets can be databases, hosts, listeners, applications, agents, and so on. You can tell Database Control to watch metrics and policies, and alert you when certain conditions are met. Determine metrics and policies indepen- dently for each target type. Database Control organizes them this way so they’re easier to administer. Metric and Policy Settings are listed in the Related Links section under each target’s main administration page. This is how it’s done for the target type database: 1. Click the Database tab on the top of any screen in Database Control to take you to the database home page. You’re taken to the database home page. The Database tab is on every Database Control page. Figure 13-4 shows the tab at the top of the page. 2. Once you’re back on the database’s home page, scroll to the Related Links section. The related links section only shows up from the database’s home page, which you access by clicking the Database tab at the top of any screen. 306 Part III: Caring for an Oracle Database Figure 13-4: The Database tab is at the top right of any page in Database Control. 3. Click the Metric and Policy Settings link in the Related Links section. You’re taken to the Metric and Policy Settings page, as shown in Figure 13-5. 4. Click the Metric Thresholds tab. Figure 13-5: Top of the Metric and Policy Settings page. 5. Choose All Metrics from the drop-down menu. You can monitor literally dozens of data points. Many you won’t care about; some are critical to you. Each metric has two thresholds: • Critical • Warning You can adjust these values independently of one another. If a thresh- old’s exceeded, a notification appears under the Alerts section of the target’s main page, and you can get an email. 6. To review your policy settings, click the Policies tab. Each policy has a description. Click the Edit icon to change a policy’s threshold. Policy violations register on the target’s main page under the Policy Violations section. You don’t have to monitor certain metrics or policies. For metrics, set the value for both Critical and Warning thresholds to Null. For policies, check the box next to the policy name and click the Remove button. 307 Chapter 13: Monitoring and Managing with Enterprise Manager We could spend an entire book just explaining all the metrics and policies that are available by default. However, it is probably easier for you to access Oracle’s free documentation available online for a complete reference. Setting Up Notifications One of the nicest features OEM offers is the ability to monitor and notify. You could spend weeks writing your own shell scripts to capture, measure, and eval- uate hundreds of different metrics on the system. In fact, we’ve seen people do this. You could also spend thousands of dollars on third-party monitoring tools. No shortage of companies have developed fancy graphical interfaces for Oracle. Despite all this, we encourage you to investigate what Oracle has to offer from within. Then make any decisions on third-party software. We aren’t saying one is better than the other. Oracle also requires licensing fees. However, the con- venience of having well-supported, built-in features has advantages. Set up notifications with these steps: 1. Log in to Database Control. 2. Click the Setup link. You’re taken to the Enterprise Manager configuration page. Here you see options for controlling your Database Control environment. 3. Click the Notification Methods link. You’re taken to a screen for configuring your mail server settings. 4. Fill in the fields, shown in Figure 13-6, with the correct information: • Outgoing Mail (SMTP) Server. Name or IP address of your outgo- ing mail server. • User Name. Optional. In the event your SMTP server requires authentication to send messages, you can put the username in here. • Password. Optional. Some mail servers require authentication to send messages. This field is for the password. • Confirm Password. Optional. Some mail servers require authenti- cation to send messages. • Identify Sender As. For indentifying the message. In Figure 13-6 the sender is simply Oracle. • Sender’s E-Mail Address. For indentifying the message. In Figure 13-6 the email address is oracle@perptech.com. You may have to team up with your mail server administrator to get some of the required information. 308 Part III: Caring for an Oracle Database 5. Click the Test Mail Servers button. This helps make sure Enterprise Manager can communicate with the mail server. 6. When you’re satisfied, click the Apply button. Figure 13-6: Notification Method set up in Enterprise Manager. To combat spam, some mail servers reject messages that don’t have a valid domain name. We’ve seen people use server names for the email domain. Usually, these servers don’t match a valid domain name and they will be rejected by the mail server delivering your email. This could be a serious problem as you might not get important alerts. Setting Up User Notifications An important part of being a database administrator is keeping on top of problems or events in the database. You can’t stay logged into Database Control watching the Alerts section for new events. Luckily, Enterprise Manager can email and page you when certain events occur. You can alert different users for specific situations and on specific schedules. This option is especially nice when your company has a rotating schedule for who services these events. You may have already configured notifications (when we discuss how to create users earlier in this chapter). However, if you didn’t do it then, here’s how to do it after the fact: 1. On the Database Control home page, click the Preferences link. Preferences are controlled by the user who’s currently logged in. If you want to set up your own notification preferences, you have to be logged in as yourself. After clicking the Preferences link, you’re taken to your account’s General settings page. You see either a list of email address or an empty section for you to add them to. 309 Chapter 13: Monitoring and Managing with Enterprise Manager 2. Click the Add Another Row button. You see the output as shown in Figure 13-7. Figure 13-7: Adding an email address for notifications. 3. Type the email address in the E-Mail Address field. You can only enter one address at a time. If you want to add an address, click Add Another Row. 4. When you’re finished adding addresses, click the Apply button. Message Format offers a drop-down list. If you’re emailing a pager, you might want to specify the short format. You won’t get as many details, but it works better with a device that sends and receives only small messages. To remove addresses, just click the Select box next to the address and then click the Apply button. Then test the addresses. 5. Check the Select box next to the address you want to verify; then click the Test button. 6. Make sure the account gets a test email from Database Control. Now set the alert schedule. 7. Click the Schedule link on the right of the page. That link takes you to a calendar-type module. 8. Click the Edit Schedule Definition button. 9. Choose one of the following options: • Rotation Frequency: Customize the times and days within the rotation frequency to repeat cycles. • Edit Existing Schedule: Adjust a schedule you’ve already set up. • Replace Existing Schedule/Start Date: Start over with your sched- ule and decide when notifications should begin. • Time Zone: This is typically the time zone you live in, not the time zone where the database resides. 10. Click the Continue button. 310 Part III: Caring for an Oracle Database 11. Complete the Email Addresses field. 12. Enter the times you’d like to be alerted. Alerts only work for one-hour increments. Click the Batch Fill-In button for tools that help with blocks of time. Figure 13-8 shows that author Chris Ruel will be on call Monday through Friday, from 5:00 p.m. until 9:00 a.m. 13. Click the Finish button. You’re shown your new schedule. Figure 13-8: The Batch Fill-In screen completes blocks of time. 14. Click Subscribe for the events you want alerts for. 15. Click the Rules link. Enterprise Manager comes with a list of rule sets; you can subscribe to them. A rule set is a list of metrics and policies. Based on your metrics and policies settings, when thresholds are triggered, an alert goes to the people subscribed to that rule. The supplied rules are convenient for quick setup. The supplied rules typically alert you to more than you might be concerned about. Try making some of your own rules. You need to know if the database is down or a tablespace is filling up. Come up with a short list of critical situ- ations that require immediate alerts and click the Create button (above the rule set). Use the tabs to add metrics, policies, and thresholds. 16. Click the Subscribe (Send E-Mail) check box for anything you want notifications for. 17. Click Apply to finish. All metrics and policies show up in the Alerts section of the main page of Database Control. Check that list daily, if not more often. 311 Chapter 13: Monitoring and Managing with Enterprise Manager Navigating Database Control’s Main Page The good news is the Database Control interface is fairly intuitive. You learn it quickly if you use it regularly. The Help link at the top right and bottom-middle of every page is useful. Depending on what section you’re in, the Help link takes you to data on that specific topic. We offer a few tips for getting around the major sections. Inspecting the Database Control main page Figure 13-9 shows the top part of the Database Control main page as it looks when you first log in. You might call this the dashboard. It gives an idea of your database’s overall health. Each monitored component in Database Control is a target. Each target has its own dashboard. Figure 13-9: The top half of the Database Control main page is chock-full of data. The database target is the dashboard you see when you first log in. All the other major sections are listed and separated, according to task, immediately under the target name. 312 Part III: Caring for an Oracle Database As shown is Figure 13-9, tabs march along the database name: ✓ Home: Using this link will always take you to the main “dashboard” of that target. ✓ Performance: This tab will give you an overview of the performance of the database. You will see things like I/O, CPU usage, top sessions, locks, etc. It contains anything that might help when diagnosing performance problems on the system. ✓ Availability: This section deals with backup and recovery. It can be con- sidered the GUI of the RMAN tool discussed in Chapter 8. ✓ Server: This section controls the “meat” of the operational portions of the database. You control space, security, initialization parameters, resources, and scheduling tasks all from this section. ✓ Schema: As this section is named, it deals with all objects in the data- base. You can change objects, add new ones, and delete them from this section. ✓ Data Movement: This section contains all the tools necessary for load- ing and unloading data. It can be considered the graphical interface for tools normally used from the command line such as SQL*Loader or Data Pump. You can also clone databases and set up replication from within this section. ✓ Software and Support: This section is helpful for things like patching, viewing, and testing configuration changes and deploying new code. Look at Figure 13-10 for the lower half of the Database Control main page for the target type database. Each section has links you can follow to investigate specific events. In some cases, a wizard is launched to interactively help diag- nose problems. Figure 13-10: The Lower half of the main control page for the target type database. 313 Chapter 13: Monitoring and Managing with Enterprise Manager ✓ Alerts: A list of events triggered by the current target’s metric and policy settings. ✓ Related Alerts: Alerts for metric and policy violations for other targets that are related to the current target. ✓ Policy Violations: Specific list of the current target’s policy violations. ✓ Job Activity: Output or recent job activity. Accessing other targets As mentioned earlier, each target has its own dashboard page. From the database target dashboard, you can access the other targets that Database Control monitors. Follow these steps to access the host or listener target dashboard: 1. Click the Home tab for the database. Under the General section on the top left, you see links for the host and listener. 2. Click the links for the target you want to know more about. You’re taken to each target’s dashboard. 314 Part III: Caring for an Oracle Database Part IV Inspecting Advanced Oracle Technologies In this part . . . Rolling back might become a necessity; every database crashes. Chapter 14 details tools you rarely see but that make your recovery easier. Chapter 15 helps ensure your database is up and running as much as possible, even when recovery is occurring. Chapter 14 Flashing Back and Replaying: Advanced Features In This Chapter ▶ Visiting the flashback database ▶ Flashing back to the data archive ▶ Replaying the database This chapter details features that you don’t see on most Oracle enter- prises day to day. (Of course, someone out there will disagree and we apologize.) Regardless, most DBAs who are new to the sport probably won’t start here; these features are for more advanced administration. You might assume these things are related: ✓ Flashback database ✓ Flashback data archive ✓ Database replay Each of these features is used to a different end. This chapter explains how these features can add value to your Oracle environment. Rolling Back with Flashback Database Have you ever wanted a time machine? No such thing exists. Or does it? The Oracle time machine known as flashback database lets you rewind, fast for- ward, and recover from situations with ease. Flashback database can sound intimidating, but the feature is simple. 318 Part IV: Inspecting Advanced Oracle Technologies You could argue that moving the database forward and back with Oracle Recovery Manager with good backups is possible. However, restoring a large database to a previous point is time consuming and tedious. Also, if you don’t go back far enough, you have to start all over from the beginning. Flashback database works by recording extra information that allows you to roll back transactions without doing a full database recovery. Not only that, but it works very quickly. The flashback database has these quick features, among others: ✓ You can open the database read only to see if you went back far enough. ✓ Not far enough? Quickly roll back further. ✓ Too far? Roll forward again. You can perform all these tasks with simple commands inside SQL*Plus or Oracle Enterprise Manager. To do them with RMAN, you’re talking multiple full restores and lots of time in between. Configuring and enabling a flash back Oracle stores a file called a flashback log. Flashback logs have the data to roll back blocks to a previous time. Flashback logs are stored in the flash_ recovery_area. Chapter 8 shows how to configure the flash recovery area. Two variables come into play here: ✓ How far back do you want to go? ✓ How much data is changed in your database within that time period? The further back you go and the more changes you have, the more flashback logs you generate. Be sure you have enough space to store those logs or you won’t be flashing anywhere. If you’re considering implementing flashback database, you may need to enlarge the parameter db_recovery_file_dest_size. By how much depends on the two variables: how far back and how much data? If you want a good start- ing point, use this formula: New Flash Recovery Area Size = Current Flash Recovery Area Size + Total Database Size × .3 In essence, you are trying to reserve roughly 30 percent of your total data- base size in the Flash Recovery area for flashback logs. From then on, you can monitor how much space the flashback logs are con- suming. We show you how to do that shortly. 319 Chapter 14: Flashing Back and Replaying: Advanced Features Once you configure the flash recovery area, turn on the flashback feature in the database: 1. Consider how far back you want to be able to flash back. Configure this setting with the parameter db_flashback_retention_ target. The default value is 24 hours (or 1,440 minutes). Say you want to be able to flash back up to 48 hours. 2. Log into SQL as SYSDBA and type the following: You should see the following for any amount of time you choose. In this example time is set to 2,880 minutes. System altered. 3. Shut down your database and restart it in mount mode. 4. Put the database in flashback mode by typing this: You should see this: Database altered. 5. Open the database by typing this: You should see this: Database altered. Now that the database is in flashback mode, you can flash back to any time within your flashback window. You might want to flash back for these reasons: ✓ Repeated testing scenarios: Say you have an application that you’re testing in your development environment. Every time you run the appli- cation, it changes your data. You will want to reset the data back to its original values before the next test. Flash back is an excellent tool for this. ✓ Logical Data Corruption: Perhaps someone accidentally ran the wrong program in your production environment; you need to return to a point before the mistake occurred. You could do this with a data recovery, but flashback is quicker and easier. ✓ Deployment procedures: Perhaps you’re releasing a new version of your code that updates all sorts of objects in your production schema with both DDL and DML. You can easily roll it back if the application isn’t working properly in target performance parameters. 320 Part IV: Inspecting Advanced Oracle Technologies Using restore points Flashing back a database is time based. Normally, you select a time and tell the database to go back to that time within the flashback window. However, another convenient feature — a restore point — is a named, easily identified point for locating a specific instance in the past. Say you’re doing a code deployment and want to mark when the database will be returned to if you have to back out the change. You could record the time, but Oracle may not get it exact when you flash back. Buck the margin of error and create a restore point — an exact time. Oracle has a margin of error of plus or minus a few seconds. To create and name a restore point, follow these steps: 1. Log into the database as SYS. 2. Type the following with your restore point name: You should see this: SCN TIME NAME ---------- ----------------------------------- --------------------- 22783928 15-SEP-08 01.15.01.000000000 PM PRE_DEPLOY_15SEP2008 ✓ Create a restore point that’s guaranteed forever. Be careful using that method: Your flashback logs grow until the restore point is dropped. You should see this: Restore point created. ✓ Drop the restore point when your code release succeeds: drop restore point PRE_DEPLOY_15SEP2008; You should see this: Restore point dropped. 321 Chapter 14: Flashing Back and Replaying: Advanced Features Flashing back your database When the database must be flashed back, don’t worry. The process is rela- tively easy. Flashing back a database removes any change that occurred after the point in time chosen to return. Don’t take this consideration lightly. To start off, say you haven’t created any restore points and want to see how far back you can go. Type this: < select oldest_flashback_time from v$flashback_database_log;> You should see something like this: OLDEST_FLASHBACK_TIM -------------------- 14-SEP-2008 06:34:03 db_flashback_retention_target should be about the limit of that time frame. You may find it to be longer if space isn’t a concern and the database hasn’t yet purged old flashback logs. Say a user accidentally dropped the HR schema from your database about an hour ago. 1. Shut down your database. 2. Restart it in mount mode. 3. Type the following, where 1 is the number of hours you want to flash back: < flashback database to timestamp sysdate - 1/24;> You should see this: Flashback complete. 4. Check the flashback before making it permanent: < alter database open read only;> You should see this: Database altered. 5. If you’re satisfied with the result, go to Step 6. If you’re not satisfied with the time, skip to Step 9. 6. Shut down the database. 7. Start the database in mount mode. 322 Part IV: Inspecting Advanced Oracle Technologies 8. Open the database with Resetlogs: < alter database open resetlogs;> You should see this: Database altered. 9. Restart the database in mount mode. 10. Type the following: You should see this: Media recovery complete. 11. Start your database in mount mode. If you want to flash back to a timestamp, go to Step 12. If you want to flash back to a previously created restore point, go to Step 13. 12. Type the following: You should see this: Flashback complete. 13. Type the following if you want to use a restore point: You should see this: Flashback complete. Using Flashback Data Archive Flashback data archive is a database mechanism that allows you to periodi- cally or indefinitely store all row versions in a table over its lifetime. You can then choose a time to view the data as it existed at a specific point in time. No need to code complex triggers to move rows to history tables. You also won’t need to code complex application logic to retrieve the data. The archiving is completely transparent to developers and end users. Oracle has sometimes referred to this feature as Oracle Total Recall. (No, that’s not a ref- erence to some cheesy 1990s movie.) When you enable flashback data archive, the row versions are automatically compressed to conserve space. You can also specify the retention period. 323 Chapter 14: Flashing Back and Replaying: Advanced Features You can’t do certain operations (such as DROP or TRUNCATE) on tables where you’ve enabled flashback data archive. Furthermore, you can’t modify historical data; this ensures the validity and consistency of the archive data. Flashback data archive is a totally online operation. No downtime is required to enable or use this feature. It’s enabled on a table-by-table basis. You can also group objects according to retention periods for easier management. Indexes aren’t maintained, but you can create your own index to facilitate searching. After the specified retention period expires, data is automatically purged to conserve space. If space is a concern, you can set quotas to limit archive growth. Also, to best organize your flashback data, create tablespaces to store flashback data for specific retention periods. If an archive quota is exceeded, new transactions are blocked. Keep an eye on space usage and periodically check the alert log for space warnings. Here’s how you might use a flashback data archive: 1. Create a tablespace that holds data for a one-year retention period: The tablespace in this example is named for documentation purposes. You see this: Tablespace created. 2. Create a flashback data archive object in your tablespace with a one- year retention and a 10GB space limit: 3. Enable flashback data archiving on the table to keep row history: You see this: Table altered. 4. Query the table to see what it looked like: Basically you’re querying the DBA_WORKLOAD_REPLAYS table. You see this (or something like it): ID NAME STATUS DURATION_SECS ---------- -------------------- ----------- ------------- 10 REPLAY_DEMO IN PROGRESS 369 You can create a replay report by using the commands shown in Figure 14-1. 328 Part IV: Inspecting Advanced Oracle Technologies Figure 14-1: Create a database replay report in SQL*Plus with these commands. When everything is done, you should clean up the replay metadata. 1. Capture ID info on the source system: You might see something like this: ID NAME ---------- ----------------------------------- 10 REPLAY_DEMO 4. Delete the replay information: Chapter 15 Using High-Availability Options In This Chapter ▶ Using Real Application Clusters (RACs) ▶ Understanding Data Guard Ahigh-availability architecture combines hardware and software solutions to help reduce the impact of outages during planned and unplanned downtime. Your data’s availability is of utmost importance. However, the level of availability varies by business. Some can deal with a little downtime here and there with minor business interruptions. A minute of downtime for others can cost tens of thousands of dollars. Luckily, Oracle helps harden against the forces out there that want to make your database unavailable. Implementing a high-availability architecture may not be cost effective for everyone. It can be expensive in terms of hardware and software licenses. However, if downtime costs you thousands of dollars in short intervals, look at some of Oracle’s high-availability options. This chapter is about a couple of Oracle features that you can configure for high availability. Each feature has its strengths and weaknesses. You some- times can combine features to get the best result. And because licensing Oracle options seems to change constantly and varies from site to site and version to version, we’re deferring any questions about the licensing of these features to your friendly Oracle sales rep. Lastly, entire books and weeklong classes deal with these technologies. We give an overview within this chapter. Unfortunately, we can’t prepare you for an enterprise installation and configuration of these options. Consider this a guide with tools that help you investigate. 330 Part IV: Inspecting Advanced Oracle Technologies Gathering Real Application Clusters If you’ve visited Oracle’s web sites in the last eight years, you’ve seen their marketing byline: “Unbreakable.” That tag line relies on Real Application Clusters (RAC). Of courses, a lot of elements are involved, but RAC has the spotlight. RAC is Oracle’s clustering solution. In a sense, it works on the theory that there is strength in numbers. RAC lets you have parallel database instance operating environments. These instances cooperate to share work and back up each other in the event one has an outage. RAC can help with both planned and unplanned outages. It allows you to shift your processing from server to server with little to no interruption to your end users and applications. Determining whether RAC is right for you is a big decision. Implementing RAC requires lots of resources and money. Just like many things, sometimes spending a little more up front will save you later. Consider what RAC can offer: ✓ Scalability. The technology is based on computers and resources that team up as one. With RAC, you can purchase and license hardware as you need it. Furthermore, you can plug the new hardware in as you go without taking down your database. If you’ve exceeded your computing capabilities for the server, seamlessly add one to your configuration. ✓ Uptime. RAC can harden your computing environment against planned and unplanned downtime. You can transparently remove portions of the application for planned downtime (such as maintenance, patches, and upgrades) with little to no interruption to end users. Furthermore, if one of your environment’s computing resources fails, RAC automatically transfers application connections to other resources in the framework. ✓ Performance. Some might argue with this point, but you have to care- fully define RAC’s performance capabilities: • Because RAC is a complicated environment, your application has to be designed to best take advantage. If you ignore this fact, RAC can actually hurt performance. Keep that in mind. • RAC can offer performance benefits when it comes to the divide- and-conquer methodology. You can split large jobs across com- puters. If you know an underpowered machine is limiting your company, reconfiguring the job to run on multiple machines can offer great benefits. It’s called parallel processing and it’s part of RAC fundamentals. 331 Chapter 15: Using High-Availability Options Exploring RAC Architecture RAC works through a complex organization of hardware and software config- urations. Mostly throughout this book we talk of Oracle databases as a single set of files (the database) and a single set of memory and process compo- nents (the instance) that work together for you to access and maintain your data. That is the most typical configuration for an Oracle installation. In this configuration, the database files can only be mounted and accessed by one machine and one Oracle instance at a time. With RAC, those files are sharable so many machines and instances can access the same files. There can be (depending on certification and versions) 100 database instances accessing the same shared database. Just like you might have two DBAs in your office: ✓ One can vacation while the other works (read: high availability). ✓ Both can work together on a large project to split the workload and meet an aggressive timeline (read: performance). ✓ Add a third person to meet workload requirements as the Oracle responsibilities grow (read: scalability). Many components are required in a RAC setup. To give you a general idea on what the architecture looks like, refer to Figure 15-1. Hardware considerations for RAC RAC has some hardware requirements. RAC versus OPS RAC, which has been around for many years, was previously known as the parallel server option. Before we get flamed about when RAC was RAC, we’re perfectly happy to admit that before the RAC moniker, Oracle Parallel Server (OPS) was far from the capabilities that RAC has to offer. Oracle significantly hardened the archi- tecture, made it more accessible and easier to set up. They also focused on the components of the environment that minimize downtime. So, you could say that RAC is a new breed of OPS that far surpasses prior capabilities. 332 Part IV: Inspecting Advanced Oracle Technologies Figure 15-1: This com- mon RAC architecture shows some of the major required components. Cluster Interconnect Central Storage Node1 Node2 Node3 NodeX Nodes A node is a server that runs an Oracle instance. A true RAC configuration has at least two nodes. The number of nodes in your RAC configuration depends on hardware and software limitations. According to Oracle’s documentation and support web sites, Oracle software itself can support up to 100 nodes, but other forces may limit you to fewer. If you’re getting into lots of nodes (more than eight), check with all your hard- ware and software vendors to see what your limit is. Add nodes as you scale your cluster. You can add and remove them with minimal or no service interruption to your application. This ensures high availability. Typically, each node will have its own installation of the Oracle software. You can have one central, shared software directory for each node to use. However, a configuration like this limits your high-availability capabilities. For example, one advantage to installing the Oracle software on each node is the ability to individually patch the nodes by taking them down one at a time. This rolling patch avoids a complete application outage. You can’t apply all patches this way. Check with patch documentation to be sure. On the other hand, one central installation requires you to shut down the entire cluster to apply the patch. 333 Chapter 15: Using High-Availability Options Each node should have its own Oracle software code tree if you want high availability. Central storage Some RAC configuration central storage requirements are discussed here: ✓ All your database files, control files, redo logs, archive logs, and spfile should be on shared storage. This way, each of the nodes has access to all the required files for data access, recovery, and configuration. ✓ Attach the central storage to each node in the form of some high- speed media. Lots of high-speed connections (fiber channel or iSCSI, for example) are available from different storage vendors. Make sure the storage and attachments are approved for Oracle RAC before making your decisions. (For example, NFS mounting drives to each server isn’t typically a certified configuration.) You can use almost any shared stor- age configuration with decent education and testing results. ✓ When choosing a storage vendor, consider your applications’ perfor- mance needs. Your disk subsystem should be able to scale as easily as your RAC nodes. As you add nodes, you may need to add physical disks to support the increased demand on the storage subsystem. You should be able to do this with little or no downtime. ✓ The disk on the shared storage subsystem must be configured for shared access. You may have up to four choices for this: • Raw file system (unformatted disks) • Oracle Cluster File System (OCFS) (available on Windows and Linux only) • Oracle Automatic Storage Management (ASM) (an Oracle-supplied volume manager of sorts for database-related files) • Third-party solution (such as Veritas) You may have to combine options. For example, you might use Oracle ASM for your database files, but you need something other than ASM for cluster software-related files. Cluster interconnect The cluster interconnect is a dedicated piece of hardware that manages all the inter-instance communication. A lot of communication across instances occurs in a RAC configuration: maintaining consistency, sharing lock informa- tion, and transferring data blocks. 334 Part IV: Inspecting Advanced Oracle Technologies Oracle uses Cache Fusion for managing data transfer between nodes. Cache Fusion requires an extremely reliable, private, high-speed network connect- ing all the nodes. Cache Fusion is a critical component for getting RAC to perform well. The interconnect needs to be gigabit speeds or better. When you have cluster communication performance issues, the intercon- nect’s ability to provide the required bandwidth is questioned. It’s a neces- sary expense to set up a RAC environment appropriately. Would you spend thousands of dollars on a race car and then put street tires on it? Network interfaces Make sure you have the right network interfaces on the server for proper communication. This includes multiple network interface cards: ✓ One for the public or user connections to the machine ✓ One for the private interconnect for the cluster to share information across the nodes. At the very least, a RAC configuration should have two network interface cards: ✓ One is for the private network for cluster interconnect traffic. ✓ One is for the public network. The public network is the connection for all cluster connections, from your applications and end users (including you and the sys admin). Software considerations for RAC Before you set up RAC, investigate the software it needs to run smoothly. Consider the following areas of software. Operating system Though nearly all popular OSs run a RAC installation, you need to ✓ Verify that the OS is certified. ✓ Make sure the right release and patchsets are confirmed as RAC certified. ✓ Ensure your Oracle version is certified with your OS configuration. 335 Chapter 15: Using High-Availability Options Oracle’s support web site (http://metalink.oracle.com) provides a matrix to help you identify certified combinations. Furthermore, an uncertified OS may be certified later. It can be complicated at first, but getting this right off the bat goes a long way down the line. Clustering software Arguably, clustering software is the most important piece of software. Without clustering software, there is no cluster. The software tracks cluster members such as databases, instances, listeners, and nodes. Lots of other cluster components run on each of the nodes and require maintenance for the clusterware to work properly. The clustering software tracks these components and facilitates internode communication and health. Depending on your experience level with different types of clustering soft- ware, you might choose one over the other. Oracle provides clustering soft- ware in the form of Oracle Clusterware. Since Oracle 10g, Oracle Clusterware is available for almost all the major operating systems. If you go with third-party clustering software, make sure it’s certified by Oracle for RAC. Veritas and Sun Cluster are examples of certified third-party clustering software. However, make sure they’re certified for your OS. Oracle database The Oracle database software is nothing special when it comes to RAC. You don’t need to download any special components or anything to make an Oracle database RAC ready. RAC is built in to the database software. When you go to install Oracle RDBMS on a cluster, it will recognize that a cluster exists and ask if you would like to do a cluster install. It’s as simple as that. Optional software You might want to use some optional pieces of software: ✓ Oracle Agent: If you manage your database with Oracle Grid Control, you need to install an agent on the cluster. Like the database software, the agent recognizes that it’s being installed on a cluster and configures itself appropriately. ✓ Oracle ASM: Though included with the database software, it’s generally good practice to install Oracle ASM into a home separate from the data- bases that run on the nodes. That way it can be maintained separately. With ASM in a separate home, you only have to shut down the one data- base you have to patch; uptime is preserved for everyone else. Of course, if all the databases use the same home, this option might not work. 336 Part IV: Inspecting Advanced Oracle Technologies Preparing for a RAC Install Each OS has its own configuration for a RAC install. It’s virtually impossible to cover everything here. However, we can offer a few pieces of advice: ✓ Thoroughly read the Oracle clusterware installation guide for your spe- cific OS. What applies on one OS may not fly on another. ✓ Be consistent across all nodes when naming users, groups, group IDs, and user IDs. Make sure the same user owns all the Oracle software components. For example, on Linux, oracle is typically an account that owns the Oracle software installation. Create this user exactly the same way as you go to all the nodes. Linux has at least two OS groups for Oracle (dba and oinstall). These must be identical. For the users and groups, this goes for the group ID (gid) and user ID (uid) as well. gid and uid maintain permissions at the OS level. If they’re not identical across nodes, permis- sions won’t be maintained correctly and the cluster won’t function. ✓ Set up the hosts file correctly. This goes for all RAC installations. The clustering software uses the hosts file to install the software and main- tain communications. The domain name server, or DNS as it’s some- times referred to, doesn’t substitute for this. You can add the host configuration to the DNS if you want, but make sure the hosts file is properly configured. Here is an example of what a two-node RAC host file may look like: 127.0.0.1 localhost.localdomain localhost 192.168.100.11 node1-priv.perptech.com node1-priv # node1 private 192.168.100.12 node2-priv.perptech.com node2-priv # node2 private 192.168.200.11 node1.perptech.com node1 # node1 public 192.168.200.12 node2.perptech.com node2 # node2 public 192.168.200.21 node1-vip.perptech.com node1-vip # node1 virtual 192.168.200.22 node2-vip.perptech.com node2-vip # node2 virtual • Each cluster node connects to another through a private high- speed network (cluster interconnect). • The public IP used for all user communication to the nodes isn’t related to the interconnect. • Each cluster node also has a virtual IP address that binds to the public NIC. If a node fails, the failed node’s IP address can be reas- signed to another node so applications can keep accessing the database through the same IP address). 337 Chapter 15: Using High-Availability Options ✓ When using Oracle Clusterware, install it in a directory that’s not a subset of your Oracle base. For example: ORACLE_BASE=/u01/app/oracle ORA_CRS_HOME=/u01/app/crs You must set many permissions under the clusterware home for special root access. You don’t want those settings to interfere with the database software installation. ✓ When using Oracle Clusterware, correctly set the permissions: • Make sure permissions are right for the directories with the voting disk and the cluster registry. This step is easy to miss. • Make sure the permissions on those directories are set to stay the same on system boot up across all the nodes. Otherwise, you can’t complete the clusterware installation or a node reboot may either cause the clustering services to not rejoin the cluster or the node to continually reboot itself. ✓ Configure the nodes in your cluster to be able to use the following: • rsh or ssh (ssh is recommend if you’re on 10gR1 or greater.) • rcp or scp (scp is recommend if you’re on 10gR1 or greater.) • User equivalence for non-password authentication The communication and copying features are for software installation and patching. They aren’t required for RAC to work after the fact. Tools for managing a RAC installation Oracle supplies several tools for managing a RAC installation. Some of the tools are RAC specific, while others are also for non-RAC databases. All the tools for both RAC and non-RAC databases become cluster aware when you launch them in the presence of a clustered environment. This means that they will see the cluster and all the nodes in it. Cluster awareness is extremely handy because a lot of the things you do in one node have to be done across many of the nodes. Cluster-aware tools help you accomplish those tasks more easily. Oracle Universal Installer for clusterware If you choose Oracle Clusterware as your clustering software, right off the bat the Oracle Universal Installer (OUI) makes the software stack installation easy. 338 Part IV: Inspecting Advanced Oracle Technologies As long as you meet these two criteria, the OUI begins by installing the software from one node and then replicates across the entire cluster: ✓ Correctly configure the hosts file across all the nodes ✓ Enable user-equivalence, ssh/rsh, and scp/rcp for the Oracle user across all your nodes This way, you only have to install the software once. (You still have to run a couple of configuration scripts on the remaining nodes after the initial install on the primary node.) Furthermore, if you ever want to add a node to the cluster, with OUI you can use the primary node to clone the software across the network to the new node. Oracle Universal Installer for other software After you configure the clusterware on the nodes, the OUI is cluster aware for all installs thereafter. That means every time you go to install Oracle software, it asks you to choose the nodes you want to do the install on. This is very nice when you do your database and agent installations. Furthermore, all patch- sets that you apply also give you the option of pushing out to all the nodes. Of course, if you’re patching in a rolling method, you can apply it one node at a time (hence, roll from one node to the next). Database Configuration Assistant (DBCA) You use this tool to create a database in Chapter 4. When the DBCA is launched from a node in a cluster, it too is automatically cluster aware. It begins the database creation and configuration by asking on what nodes you want to perform operations. To create a four-instance cluster across four nodes, you only have to log on to one of the servers and do it all from the DBCA. This huge time saver automatically sets all the special initialization parameters for each node in each instance. Network Configuration Assistant (NETCA) When it comes to managing listeners and tnsnames files, NETCA is also clus- ter aware. If you need to add a listener or tnsnames entry, any action taken on one node is automatically propagated with appropriate settings across all the nodes. Configuring all the listener.ora and tnsnames.ora files across a multimode cluster would take a week by hand. Server Control (srvctl) Server Control is probably your day-to-day main command-line tool for man- aging your RAC environment. 339 Chapter 15: Using High-Availability Options To see an abbreviated list of all the things you can do with this tool, open a command-line prompt on your OS and type this: You see something like this: Usage: srvctl [] command: enable|disable|start|stop|relocate|status|add|remove|modify|getenv| setenv|unsetenv|config objects: database|instance|service|nodeapps|asm|listener For detailed help on each command and object and its options use: srvctl -h The server control utility lets you manage nearly all the resources across the entire cluster from one session. Say you’re logged into node1 and want to shut down the instance prod31 on node3 for the database prod3. This is what you’d type: You should see this: That’s right: Nothing. You see nothing if it works correctly. If you get errors, research appropriately. You can use Server Control to do the following and any combination therein: ✓ Stop all instances of a database ✓ Stop two of five instances for a database ✓ Start all instances ✓ Stop one or all listeners You can easily script Server Control into operating scripts. That’s one of its big benefits. Tools like SQL*Plus and the listener control utility (which require an execution on each node for multi-node operations and multi-line inputs) make for more complex scripts. With Server Control, everything is contained in one line for whatever operation you want to accomplish. Cluster Control (crsctl) Cluster Control is another command-line tool that controls the cluster-specific resources. It can start and stop the cluster components on individual nodes. Type this to launch cluster control and get a list of the command options: 340 Part IV: Inspecting Advanced Oracle Technologies You see something like this: Usage: crsctl check crs - checks the viability of the Oracle Clusterware crsctl check cssd - checks the viability of Cluster Synchronization Services crsctl check crsd - checks the viability of Cluster Ready Services crsctl check evmd - checks the viability of Event Manager crsctl check cluster [-node ] - checks the viability of CSS across nodes crsctl set css - sets a parameter override …output snipped… crsctl query crs activeversion - lists the Oracle Clusterware operating If necessary any of these commands can be run with additional tracing by adding a ‘trace’ argument at the very front. Example: crsctl trace check css We cut a large portion of the output because this tool has a lot of options. Patching the OS is one situation when Cluster Control is useful: 1. Stop all the cluster resources on that particular node with Server Control. 2. Stop the cluster specific components: You see this: Stopping resources. Successfully stopped CRS resources Stopping CSSD. Shutting down CSS daemon. Shutdown request successfully issued. You might be required to reboot the node once or twice during the OS maintenance; you don’t want the cluster to restart. 3. Prevent the cluster services on this node from restarting: 4. Do all the reboot you want. You don’t have to worry about the cluster services interfering. 5. Re-enable the cluster services: 341 Chapter 15: Using High-Availability Options 6. Restart the cluster services: All the cluster resources start, including the database-related resources on the node. Oracle Interface Configuration Tool (OIFCFG) If you need to change the cluster (changing server name or IP addresses, for instance) you must use the Oracle Interface Configuration Tool to reconfigure those changes in the internal cluster configuration. Avoid making these types of changes. Put some thought into your network naming and IP choice ahead of time. Oracle RAC application for high availability RAC helps with high availability (HA) by providing redundancy in your envi- ronment — specifically, redundant Oracle instances. One instance in a multi- instance environment can be removed for OS, hardware, or Oracle software maintenance without disrupting the application. Extended RAC Recent developments are happening in a move- ment called Extended RAC. This RAC solution can protect against total site loss while pro- viding all the other RAC features. As network transmission speeds increase over time, some people think that RAC is possible with instances in remote locations. This configuration requires high-speed SAN mirroring and a network transmission media called dark fiber. Dark fiber is a private, direct connection between two remote sites that can handle multiple network transmissions at once over the same cable using varying light frequencies. At press time Extended RAC appears to have distance limitations. The farther apart the sites, the higher the latency. Latency turns into cluster performance degradation. We’ve been unable to find any definitive documentation on the distance limits. Degradation appears to factor heavily into your type of connection. Some sites use repeaters to extend even further. In the mean time, if you need a remote site con- figured for disaster recovery, you may want to consider Data Guard. It can offer a lot of the features that Extended RAC does but at a frac- tion of the cost with no real distance limits. 342 Part IV: Inspecting Advanced Oracle Technologies However, make sure your expectations meet what it can deliver: ✓ RAC doesn’t cover all points of failure. It definitely helps harden against node failure and instance failure. Unfortunately, it can’t help with SAN, interconnect, or user error. ✓ RAC isn’t typically considered a disaster protection solution. If your entire site was compromised by wind, fire, or water, RAC is going with it. Defending Oracle Data Guard Data Guard is Oracle’s true disaster protection technology. In it you have two databases: ✓ A database called a primary ✓ A database called a standby The two databases are connected by a network that ships all transactions from the primary and then applies them to the standby. In essence, you have one active database and one database in constant recovery. Data Guard has options for multiple standby sites as well as an active-active configuration. See Figure 15-2 for a general architectural layout. Data Guard architecture Start a description with the primary database is easy because it differs very little from any other database you might have. The only difference is what it does with its archived redo logs. The primary database writes one set of archive redo logs to a flash recovery area or a local disk. However, you may configure one or more other destina- tions in a Data Guard environment. The LOG_ARCHIVE_DEST_n parameter may look like this for the configura- tion in Figure 15-2: LOG_ARCHIVE_DEST_10=’LOCATION=USE_DB_RECOVERY_FILE_DEST’ LOG_ARCHIVE_DEST_1=’SERVICE=PHYSDBY1 ARCH’ LOG_ARCHIVE_DEST_2=’SERVICE=LOGSDBY1 LGWR’ 343 Chapter 15: Using High-Availability Options ✓ LOG_ARCHIVE_DEST_10 is configured to send archive redo logs to the local flash recovery area. One local destination is required for all archive log mode databases. ✓ LOG_ARCHIVE_DEST_1 is configured to ship the archive logs via the archiver process (discussed in Chapter 2) to a remote site PHYSDBY1. The service name for this remote site has an entry in the tnsnames.ora file on the primary server. ✓ LOG_ARCHIVE_DEST_2 is configured to ship the archive logs via the LGWR process to a remote site named LOGSDBY1. The service name for this remote site has an entry in the tnsnames.ora file on the primary server as well. Why the difference in ARCn versus LGWR shipping methods? That has some- thing to do with protection modes. A Data Guard environment has three pro- tection modes. Figure 15-2: This Data Guard architecture has one physical and one logical standby database. Primary - Active Transactions Physical Standby- Backup Database Logical Standby- Reporting Database OracleNet LAN/WAN SQL Apply Redo Apply ARC0 ARCn LGWR 344 Part IV: Inspecting Advanced Oracle Technologies Maximum availability This protection mode compromises between performance and data avail- ability. It works by using the LGWR to simultaneously write to redo logs on both the primary and standby sites. The performance degradation comes in the form of processes having to wait for redo log entries to be written at multiple locations. Sessions issuing commits have to wait until all necessary information has been recorded in at least one standby database redo log. If one session hangs due to its inability to write redo information, the rest of the database keeps moving forward. Maximum protection This protection mode is similar to maximum availability except that if a session can’t verify that redo is written on the remote site, the primary database shuts down. Configure at least two standby sites for maximum protection mode. That way, one standby site becoming unavailable won’t disrupt service to the entire application. This mode verifies that no data loss will occur in the event of a disaster at the cost of performance. Maximum performance This protection mode detaches the log shipping process from the primary database by passing it to the archive log process (ARCn). By doing this, all operations on the primary site can continue without waiting for redo entries to be written to redo logs or redo shipping; it has to wait for these events with the other protection modes. Maximum performance provides the highest level of performance on the pri- mary site at the expense of data divergence: Archive redo data isn’t shipped until an entire archive redo log is full. In a worst case scenario, an entire site loss could result in the loss of an entire archive redo log’s worth of data. Physical standby database A physical standby database is a block-for-block copy of the primary site. It is built off a backup of the primary site and is maintained by shipping and applying archive logs to the standby site in the same way the transactions were committed on the primary site. 345 Chapter 15: Using High-Availability Options Physical standby databases can’t be open for changes. You can stop recov- ery on the physical standby site and open it for read-only transactions. During this time, the standby site falls behind the primary site in terms of synchronicity. All the transactions are saved until the standby site’s recovery is reactivated after reporting operations are done. If you want a standby site available for reporting operations, consider setting up dual standby sites. That way, one can stay in recovery mode and you per- haps can open the other for reporting operations during the day; then close it at night for catchup. That way if you ever need to have a standby site acti- vated, you won’t have to wait for it to catch up first. Here’s a high-level overview of the steps to configure a physical standby database. In this example the primary site name is prod_a and the standby site name is prod_b. 1. Set various initialization parameters in the primary database to pre- pare it for redo log shipping: • instance_name (different on each site) instance_name = prod_a • db_name (same on each site) db_name = prod • remote_archive_enable (enables sending of logs to remote site) remote_archive_enable = true • log_archive_dest_1, 2 log_archive_dest_1 = ‘LOCATION=/u01/arch/prod’ log_Archive_dest_2 = ‘SERVICE=prod_b.world ARCH’ • log_archive_format (tells primary how to name local and standby logs) log_archive_format = arch_%S.arc • standby_file_management (makes adding data files easier) standby_file_management = true • fal_client (tells primary where to re-ship “lost” archive logs) fal_client = ‘prod_a.world’ Regarding Steps 1 and 6: Set all the parameters on both sites to facilitate failover/switchover operations. 346 Part IV: Inspecting Advanced Oracle Technologies 2. Create a standby copy of your primary control file by logging into SQL*Plus on the primary and typing the following: You should see this: Database altered. 3. Move this copy to the standby site and put it in the directory of your choice. 4. Modify the initialization parameters on the prod_b instance to point to the new control file. You can rename it however you want. 5. Restore a backup of your primary site to the standby site. You can do this with RMAN or traditional hot/cold backup methods. To simplify things, put the files in the same locations on the standby site as the primary. If you can’t do that, you have to rename the files once you mount the database, or use the following initialization parameters on the standby site so the instance can convert the locations. Say the files were in /u01/app/oracle/oradata/prod on the primary and /disk1/app/oracle/ oradata/prod on the standby: DB_FILE_NAME_CONVERT = ‘/u01/’,’/disk1/’ Oracle finds all instances of /u01 in your data file name and replaces them with /u02. 6. Set the initialization parameters on the standby site: • instance_name (different on each site) instance_name = prod_b • db_name (same on each site) db_name = prod • remote_archive_enable (enables receiving of logs on remote site) remote_archive_enable = true • standby_archive_dest (tells standby database where to find logs) standby_archive_dest = /disk1/arch/prod • log_archive_format (tells standby how to interpret log names, set same as primary) log_archive_format = arch_%S.arc • standby_file_management (makes adding data files easier) standby_file_management = true 347 Chapter 15: Using High-Availability Options • fal_server (tells standby where to search for “lost” archive logs) fal_server = ‘prod_a.world’ 7. Mount the standby database: You should see this: Database altered. 8. Start recovery on the standby database: You see this: Media recovery complete. 9. Log out of the standby site. Let the recovery run in the background. Logical standby database A logical standby database works by copying your primary site with a backup. Then a process called SQL Apply takes the archive logs from the primary site and extracts the SQL statements from them to apply them to the logical standby database. During this time, the logical standby database is up and open. It’s like having the best of both worlds. People can have updated data with the primary site for reporting purposes. Because the standby database will be up and open, you must protect the data from being modified by anyone other than the SQL Apply services. If the data is modified outside of this procedure, the standby database will diverge from the primary. If you ever need to switch over to it for disaster recovery pur- poses, it won’t match the primary. To prevent replicated objects in the standby site from being modified, issue the following command in the standby environment: ALTER DATABASE GUARD STANDBY; Another unique feature of a logical standby database: the ability to only rep- licate certain objects. By default, all objects are replicated. However, you can force SQL Apply processes to skip certain objects. In addition, you can con- figure those skipped objects to allow modifications to them. 348 Part IV: Inspecting Advanced Oracle Technologies Performing switchover and failover operations You can switch processing to your standby site two ways: ✓ Switchover is a planned switch that can occur if you want to do main- tenance on the primary site that requires it to be unavailable. This operation may require a few minutes of downtime in the application but if you have to do maintenance that lasts for an hour or more, it could be worth it. It is called a graceful switchover because it turns the primary site into your standby and your standby site into your primary. Also, you can easily switch back to the original primary site without having to re-create it from scratch. ✓ Failover occurs when the primary site has been compromised in some way. Perhaps it was a total site loss or maybe you discovered physical corruption in a data file. Not always, but usually after a failover, you have to either completely re-create the primary site or recover it from a backup and re-instate it. You usually perform a failover only when you’ve determined that fixing the primary site will take long enough that you prefer not to have an application outage for the entire time. To perform a switchover, follow these steps: 1. On the current primary, log into SQL*Plus and type the following: You should see this: Database altered. 2. Shut down the primary database: You should see this: Database closed. Database dismounted. ORACLE instance shut down. 3. Start the primary database in nomount mode: You should see something like this: ORACLE instance started. Total System Global Area 789172224 bytes Fixed Size 2148552 bytes Variable Size 578815800 bytes Database Buffers 201326592 bytes Redo Buffers 6881280 bytes 349 Chapter 15: Using High-Availability Options 4. Mount the database as a standby: You should see this: Database altered. 5. Start recovery: You see this: Media recovery complete. 6. Log into SQL*Plus on the current standby and type the following: You should see this: Database altered. 7. Shut down the standby database: You should see this: Database closed. Database dismounted. ORACLE instance shut down. 8. Make sure all appropriate initialization parameters are set for this database to behave properly as a primary. 9. Start it normally: You should see something like this: ORACLE instance started. Total System Global Area 789172224 bytes Fixed Size 2148552 bytes Variable Size 578815800 bytes Database Buffers 201326592 bytes Redo Buffers 6881280 bytes Database mounted. Database opened. 10. Make sure the users and applications can connect to and use the new primary instance. 350 Part IV: Inspecting Advanced Oracle Technologies Part V The Part of Tens In this part . . . Implementing a database takes many steps. Chapter 16 leads you through the top ten things you should do during installation. Chapter 17 gives you the top ten things you should do when implementing. Chapter 16 Top Ten Oracle Installation Do’s In This Chapter ▶ Reading documentation ▶ Seeing the Oracle Optimal Flexible Architecture ▶ Profiling ▶ Getting the wrong bit ▶ Forgetting to mask ▶ Becoming an Oracle ▶ Fighting stage fright ▶ Patching ▶ Fawning over user and group IDs ▶ Backing that thing up In this chapter we focus things you shouldn’t overlook when installing Oracle. Getting off to a good start with a solid, proper installation is key to success. By recognizing the common pitfalls up front, you experience less heartache and pain later on. Read the Documentation Every OS that runs Oracle has a corresponding documentation set. This doc- umentation covers things like operating system packages, kernel parameters, network configuration, and other installation prerequisites. Every operating system is different. Even if you think they’re the same, you’re wrong. UNIX is UNIX, right? Wrong. HP-UX, AIX, and Solaris each have very distinct prerequisites. Go to Oracle’s documentation on the Internet and download the latest and greatest install guide for your OS. Read it thoroughly before you begin. We even recommend listing all the little things that have to be checked before you begin. If you make this a practice, you will find far fewer problems during and after installation. 354 Part V: The Part of Tens The quickest way to get to Oracle’s documentation is here: 1. Go to http://docs.oracle.com. 2. Select the version you’re interested in. 3. When you enter the 11g documentation set, open the Installing and Upgrading folder. The folder’s on the left side of the screen. 4. Click the OS of your choice to enter the OS-specific installation guide. Observe the Optimal Flexible Architecture The optimal flexible architecture (OFA) is an Oracle guideline that lays out how software and databases should be installed on a system. The OFA has these main purposes: ✓ Find Oracle files in explicit locations, even when on multiple devices ✓ Set up a software tree that allows easy patching and upgrades ✓ Mirror Oracle installations across all environments so they’re the same or similar ✓ Keep separate Oracle files and installation types ✓ Facilitate routine management tasks ✓ Facilitate backup and recovery ✓ Manage and administer growth ✓ Facilitate layout for best performance We recommend you fully read and understand Oracle’s documentation to best implement the OFA. There are many rules and guidelines: too many to cover here. Oracle’s docu- mentation gives explicit examples and suggestions for a variety of operating systems and storage. Furthermore, OFA has evolved over the years. The main ideas remain, but some have been tweaked. For each release of Oracle, don’t hesitate to refresh yourself. 355 Chapter 16: Top Ten Oracle Installation Mistakes Configure Your Profile The profile probably applies more to UNIX-type environments. However, by learning the key elements needed inside the profile, you can also see that they may apply to Windows. The profile is the program (for lack of a better word) that runs every time you log into your operating system. It is typically found in your home directory. Depending on the shell that you use, it might be named any of the following ways: ✓ .profile ✓ .kshrc ✓ .bash_profile By configuring this script, you can take better advantage of the operating environment and your Oracle software. Different types of users also may have different profiles. Furthermore, you may have multiple profiles depend- ing on what you will do when you log in. The profile sets up variables, execution paths, and permissions and some- times limits in your session. The Oracle documentation recommends specific settings for your environment. Some are OS specific, others apply to almost all Oracle installations. Definitely include these elements in your profile: ✓ Oracle base variable ✓ Oracle home variable ✓ Path variable ✓ Default file-permission settings ✓ Aliases ✓ Library variables Without a properly configured profile, you have to change these every time you log into the system. We want to say having a profile is a requirement, but technically it’s not. However, you should make it part of your standard practice. 356 Part V: The Part of Tens Running the Wrong Bit More operating systems are offering 64-bit versions. When you install Oracle, take advantage of the appropriate bit version. The fact is, 32-bit software usually runs fine on 64-bit operating systems. It doesn’t work the other way around. Don’t spend all kinds of money on a 64-bit OS and hardware, and then install the 32-bit version of Oracle. This limits you in several ways: ✓ Your SGA can’t exceed a certain size. ✓ You can’t take advantage of the server’s faster 64-bit architecture. ✓ Multitasking can be limited. For what it’s worth, this mistake is made more often in Windows environments. When you order or download your Oracle software, ask the system adminis- trator what binaries you can use. In almost all cases, 64 bit is preferable. That goes for when you are provisioning out a system as well; 64 bit offers more scalability and increased computing power. Set umask If you read and follow the Oracle documentation, this should not be a prob- lem. Linux/UNIX environments have a umask setting. Forgetting to properly set the umask parameter means a difficult, if not impossible, Oracle installation. The result doesn’t typically affect the Oracle software owner, but the users who log in to the OS and try to use the system. umask sets the default permission modes on files and directories that are added to the system. This can affect files copied to the system during installation, as well as things like log files, which are created as part of normal operation. The Oracle-recommend umask is 022. This results in files being read+write for the owner, and read for all others. If you put the umask setting in the profile it sets each time you log in. 357 Chapter 16: Top Ten Oracle Installation Mistakes Become Oracle On a production system the Oracle database software should be installed by a user specifically created for the task. This user is typically named oracle. Imagine that. Now, this isn’t a hard and fast rule, but we recommend that you seriously consider this — especially if you’re a beginner. This is how you find it in most systems as well as training materials and documentation. Naming the user oracle avoids this scenario: The Oracle software is installed as another named user or by a user associated with a different software pack- age. You don’t want Craig installing the Oracle software stack under his own ID. He may leave the company someday and now you have a problem. It’s not best practice to let login IDs exist for people who no longer work at the company, which is a security concern not to mention confusing. Set up a dedicated ID (we recommend oracle) to install software with. This makes maintenance and training easier, and it eases personnel transitions. This recommendation also comes from Oracle. Stage It If you download the software, you don’t need it on disk for installation. We recommend keeping a hard copy somewhere for recovery reasons, but that’s about it. Even if you bought the installation CDs, copy the material to the hard drive before the installation. ✓ The install is faster if reading from disk. ✓ You don’t have to worry about someone else in the server room ejecting the disk and it disappearing forever. ✓ Having a copy of the software helps if you want to add a feature that you hadn’t installed at first. It’s easier to find it in a staging area than hunting down the disk. ✓ If the Oracle binary files are corrupt and you need to reinstall a portion of the code tree, it’s right there. 358 Part V: The Part of Tens You can get software from Oracle two ways: ✓ Order it from the Oracle store. ✓ Download it from their web site. Both copies are identical. The downloadable software isn’t a trial version. Anyone can download and use it, provided you contact an Oracle sales rep and pay for it. Patch It You just downloaded and installed your brand-new Oracle database. Now we’re telling you it needs to be patched. What?! Whether you order the CDs or download the software, you’re probably not getting the most recent version. If you’re licensed for Oracle — and you should be — log into their Oracle Support web site and search for the most recent patchsets to apply to your database. 1. Go to Oracle’s support web site at http://metalink.oracle.com. 2. Enter your login ID. If you do not have one, click the Register button and follow those instructions. 3. Enter your Customer Support Identifier (CSI). You get this when you purchase support from an Oracle sales representative. Once you log in, you see tabs across the top of the page. 4. Click the Patches and Updates tab. 5. Enter the following information: • Your OS • Software package • Database version • Type of patch or patchset We recommend being on the latest, greatest maintenance release of the Oracle software — but make sure the software is compatible with or supported by your application. 359 Chapter 16: Top Ten Oracle Installation Mistakes Many times we’ve discovered a client with an older version of Oracle. When we recommend a patch they announce they have some third-party software vendor who only certifies on a certain patch level. Despite the problems with third-party software, there are benefits to being on the latest Oracle patchset: ✓ Oracle keeps creating patches to fix bugs in the release as long as your patch level is supported. Otherwise, you’re out of luck. ✓ Quarterly Oracle security patches are usually available for the most recent patchsets only. ✓ The patchsets are maintenance releases in essence. This means that bugs found in previous releases are fixed. Despite all the good things about being on the latest Oracle patchset, read the patchset documentation before you apply the patch. Unfortunately, some- times bugs are introduced with a patchset. Make sure that any new issues don’t affect the functionality your application works with. Mind the User and Group IDs This bit of advice pertains more to Linux/UNIX operating systems. When a group or user is created on Linux/UNIX, they’re assigned a user ID number. All file ownership and permissions are based on this number. By default, the OS chooses the first available number. This isn’t where problems occur. Problems occur when you install Oracle on multiple servers — especially sys- tems using Oracle RAC or DataGuard. Due to file sharing, if the user and group IDs don’t match across the systems, they’re not going to function properly. Furthermore, if you’re shipping Oracle files across the network (transportable tablespaces or cloning, for instance), you’ll have problems reading these files when they arrive. It is best practice to specifically assign a number to your Oracle user and its associated groups when they’re created. Document this number in your com- pany’s Oracle operating procedures manual. If you have multiple DBAs or Oracle installers, use the same ID numbers across all systems. 360 Part V: The Part of Tens Back It Up You finally configured your OS, set up all the Oracle users and groups, con- figured your profile, staged the software (and its patches), installed Oracle, patched Oracle, and created your first database. Wow, that’s a lot of work. Now back up your work! Now test your backup to make sure it’s usable; see Chapter 17 for more. Besides just a backup at the end, you could do multiple backups as you go: after the OS prerequisites are done, after Oracle is installed, after the patch, and so on. That way, you can easily go back without completely starting over. Chapter 17 Top Ten Database Design Do’s In This Chapter ▶ Using Oracle’s built-in constraints ▶ Spreading out your I/O ▶ Learning data normalization ▶ Improper or inconsistent naming conventions ▶ Setting up roles and privileges properly ▶ Cutting down on ad-hoc queries ▶ Enforcing password security ▶ Avoiding too many DBAs ▶ Storing code in the database ▶ Testing recovery strategy In this chapter we focus on some of the mistakes or shortcomings we’ve seen in Oracle databases over the years. Most of these are honest mis- takes due to inexperience with Oracle or databases in general and can easily be overcome. After all, if it weren’t for things like this, DBAs like yourself wouldn’t have anything to do! Using Oracle’s Built-In Constraints Constraints enforce rules against your data. Oracle offers some of these built- in constraints: ✓ Primary keys identify a column or columns in the table whose data for the values stored is unique and non-null. ✓ Foreign keys enforce something called referential integrity. 362 Part V: The Part of Tens ✓ Check constraints are customizable constraints that check the data entered into a column. ✓ Not Null constraints disallow an empty column to be empty. ✓ Unique constraints are a column or group of columns whose values together are unique for the row. Constraints seem like a very useful and almost required feature in any data- base. Odd as it may seem, some software vendors don’t natively include a system of constraints in the database software. This requires develop- ers to code their own in the application. This can be extremely difficult and a nightmare to maintain. Not to mention the fact that they will only be enforced through the application itself. Anybody gaining access via a tool like SQL*Plus won’t be required to obey the application constraints. In some Oracle databases the designer or primary developers came from a database that required the constraints to be created and managed in the application. Make sure you don’t fall victim to this situation: Use the built-in Oracle constraints. Spreading Out Your IO When laying the files down on your system, you should make sure to evenly balance the files across the available disks. Some people might argue that their hands are tied. For systems using local storage inside the server, buy as many smaller disks as possible so you can balance your IO. These days, it seems that manu- facturers are offering ever large devices for storage. This makes your job difficult. Keep in mind that when you work with the storage/server vendor, the machine is for storing and retrieving data. By having several locations to store your data, you get more tuning capabilities. The rules for storing Oracle files can be broken down an infinite number of ways. Here are some basics: ✓ Separate tables and indexes across different drives ✓ Store your redo log groups and members separately ✓ Store unrelated to application data separately ✓ Store table partitions separately ✓ Store system files separately ✓ Store the Oracle binaries on their own device 363 Chapter 17: Top Ten Database Design Do’s You can break this down even further depending on your data access behav- ior. By using Oracle’s data dictionary and available monitoring tools, you can fine-tune the storage layout for your specific application. Knowing Data Normalization Data normalization is how you lay out your application storage needs in your tables. Before you begin designing a database from scratch, know the rules of normalization. Some developers fall victim to data normalization shortcomings because of previous experience with other databases. For example, we have seen people design data models based on their experience with Microsoft Excel or Lotus Notes. These flat file-type databases have different rules for design. Normalization is a set of rules designed for relational type databases. Spend some quality time with an Oracle data-modeling book or class before you get too far in an application design project. Using Naming Conventions This topic boils down to good data-modeling skills. When creating objects in your system, it is important to follow rules. If you do your research or take a class on data modeling, you know the guidelines. Best practice is to adhere to those as best as possible. However, the most important thing is to follow some sort of documented, repeatable guidelines everyone can easily understand. Avoid these common mistakes: ✓ Don’t use keywords. Don’t name your table table. ✓ Don’t let the system give default names. This is usually the case with constraints. Take the time to come up with something descriptive. ✓ Don’t use quotes with column names and table names. Many over-the- counter developer tools do this. Problem is you can end up with objects that have mixed-case names. Next thing you know you have tables named EMP, emp, and emP — all different. Create a document that outlines the standard practices your company will use. This will aid in the training of new hires and make sure the IT depart- ment is on the same page when working collaboratively on an application. 364 Part V: The Part of Tens Setting Up Roles and Privileges Properly While it’s tempting, make sure you don’t fall victim to taking the easy way out when configuring object access. Don’t grant everything to everybody because the design team doesn’t want to put a system of roles and privileges in place. It’s especially tempting when you need to meet a project deadline and a developer is dead in the water. Do your best to come up with different roles for your developers, application users, and application owners. This makes management and security much easier down the road. Chapter 9 deals with configuring roles and privileges in your database. This is a very important chapter not only for security but manageability. Keeping Ad-Hoc Queries to a Minimum Okay, this piece of advice is difficult to swallow. Dozens of companies offer tools that show managers how easy it is to go into a database and design all kinds of fancy reports with graphs and colors. They promise increased rev- enue and efficient information transfer. The problem is that these products are marketed to managers, not the technical team. We aren’t saying that there is no place for a tool like this. Quite the opposite. After all, the whole point of having a database is to serve up data. However, having some control over what type of reports are allowed is going to make the DBA, the system administrator, and the end users happier overall. Allowing unsolicited ad-hoc queries in your database to run any time, in any form, is asking for trouble. Not only can they run slowly, but the entire data- base can become unusable during their execution. In an ideal world, reports are designed, qualified, and approved before they’re run. A team of developers can work with DBAs and managers to list information needs. Those can be skillfully and efficiently transformed into canned reports available at the click of a button. They can be scheduled to run at specific times to avoid impacting the system. Enforcing Password Security When you create a user in Oracle, you’re forced to set a password. This is good. However, not until 11g did Oracle force you to make sure that pass- word was secure. During database creation, it asks if you want to revert 365 Chapter 17: Top Ten Database Design Do’s to the pre-11g security requirements, which were minimal. One of the first things we recommend is an overhaul of the password security system. Some common problems are easily remedied with Oracle password profiles: ✓ Lack of password complexity ✓ No regular password expiration schedule ✓ Reusable passwords ✓ Shared logins ✓ Default passwords Implementing password security through a user profile is extremely easy. Unfortunately, one of the side effects of this is that the users will hate you for it! People seems to hate having to remember a password that’s something other than their username. This is critical. Limiting the Number of DBAs Make sure that only company-approved people have access to the DBA role on the database. Not only does it threaten security but it reduces account- ability. Tracing problems is much easier when the source isn’t a group of dozens of users. Most problems we encounter are due to user error. Again, expect resistant users. Every company has that person who’s been with the team for 20 years and knows the business and application inside and out. He has always had DBA access. Problem is, he hasn’t had any formal Oracle training or experience. Do what you have to do to convince management that few people should have the keys to the kingdom. Also, make sure those people are trained and accountable for the actions they take. Storing Code in the Database SQL is the primary language for accessing and manipulating Oracle data. You can embed it in applications or store it in the database in the form of stored procedures. Not all SQL needs to be stored in the database, but consider designing the application so the bulk of the business processes is made up of stored code. 366 Part V: The Part of Tens Unless the developers are trained to take advantage of Oracle’s stored proce- dure mechanisms, you don’t have the best, most efficient database possible. ✓ Stored code enforces security. A stored procedure can be encrypted (wrapped, in Oracle terms). Users can run procedures without access to the base objects with which the code works. Stored procedures are executed with the owner’s permissions, not the user who is calling it. ✓ Stored code performs better. It is pre-compiled in the database and can be stored in memory without parsing and compiling. This decreases CPU usage and increases system scalability. Stored code is easier to maintain because it’s in one place. If you’re adding functionality or changing business rules, the application can immediately take advantage of the changes without releasing a new version. Testing Your Recovery Strategy With a little training, it’s easy to design a backup process for your system. Testing is a key element to a robust backup and recovery strategy. Running an error-free backup every night doesn’t mean you can recover with it. Now, we don’t want to be doomsday preachers. Using RMAN and getting backups with no errors mean you have a significant chance of recovery. But what if you need those backups and they don’t work? You could be, as they say, caught with your pants down. You might even be out of a job. This extends to training. Do you know what commands to issue for a recov- ery? Do you know the fastest way to recover given the specific type of fail- ure? Will you use RMAN or Flashback database? Testing your recovery strategy checks the backup itself, and lets you practice for situations where a speedy recovery is required. You don’t want to spend an hour reading the Oracle documentation. Know how to reduce the liability of your skill set by testing and practice. Appendix A Quick Start Install of Oracle 11g on Linux In This Appendix ▶ Setting up the operating system ▶ Installing the Oracle software To get you started, we included an appendix on installing the Oracle 11g software on Linux, which is a readily available, free operating system. This chapter gives you the necessary steps to install Oracle not only on the many flavors of Linux, but also applies to some UNIX systems as well. This appendix’s example uses RedHat Enterprise Linux 4 (RHEL4). This Oracle installation can test most of the features discussed in this book. We recommend having at least 2GB of memory and 10GB of free hard-disk space to do any work. Setting Up the Operating System Unlike installing Oracle on Windows, Linux environments have some installa- tion prerequisites. This appendix goes over the basic prerequisites as speci- fied in the documentation set Oracle Database Quick Installation Guide for 11g Release 1 (11.1) for Linux x86. To view this documentation set, follow these steps: 1. Go to http://docs.oracle.com. 2. Click Oracle Database documentation, 11g Release 1 (11.1). 3. Click the + next to the Installing and Upgrading folder. 4. Click Linux Installation Guides. You see Quick Installation Guide for Linux x86 on the right. That is the document you want. 368 Oracle 11g For Dummies The next section assumes you will complete the required tasks logged in as the user root. Checking your operating system version Oracle is only certified to run on particular versions of Linux. If you have trouble with your database and need Oracle support, they may insist that you be on a certified version of Linux before they help you. Use a certified version of Linux if this installation if you’re planning to purchase Oracle support. The supported versions of Linux for Oracle 11g follow: ✓ Asianux 2.0 ✓ Asianux 3.0 ✓ Oracle Enterprise Linux 4.0 ✓ Oracle Enterprise Linux 5.0 ✓ Red Hat Enterprise Linux 4.0 ✓ Red Hat Enterprise Linux 5.0 ✓ SUSE Enterprise Linux 10.0 To see what version of Linux you are on, follow these steps: 1. Open a command prompt on your OS. 2. Type this: You should see something like this: Linux version 2.6.18-53.1.14.el5 (gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)) #1 SMP Checking your kernel version The kernel is essentially the core operating version of Linux operating system. It’s kind of akin to a service pack in Windows. For Oracle to be certified, you also need to be on a certified kernel version. RHEL4’s required kernel version is 2.6.9. To see your kernel version, type this: 369 Appendix A: Quick Start Install of Oracle 11g on Linux You should see something like this: 2.6.9-55.0.0.0.2.EL Checking your OS packages Packages are modular pieces of the operating system that you can install to activate certain features. For Oracle to run on Linux, it requires particular packages. RHEL4 requires the following packages: ✓ binutils-2.15.92.0.2-18 ✓ compat-libstdc++-33.2.3-47.3 ✓ elfutils-libelf-0.97-5 ✓ elfutils-libelf-devel-0.97-5 ✓ glibc-2.3.4-2.19 ✓ glibc-common-2.3.4-2.19 ✓ glibc-devel-2.3.4-2.19 ✓ glibc-headers-2.3.4-2.19 ✓ gcc-3.4.5-2 ✓ gcc-c++-3.4.5-2 ✓ libaio-devel-0.3.105-2 ✓ libaio-0.3.105-2 ✓ libgcc-3.4.5 ✓ libstdc++-3.4.5-2 ✓ libstdc++-devel-3.4.5-2 ✓ make-3.80-5 ✓ sysstat-5.0.5 To see if a required package is installed, to use RedHat Package Manager (rpm). For example, to check the make package, type this: rpm –q make You should see something like this: make-3.81-1.1 370 Oracle 11g For Dummies If you find some packages not installed or that do not meet the required version, get them from the Linux distribution installation media or the appropriate Linux vendor’s download site. Creating Linux operating system groups and users Linux best practices entail creating specific groups and users to install, own, and maintain the Oracle software. Oracle requires two operating system groups for the software: ✓ dba controls what users can connect do on the database using operat- ing system authentication. ✓ oinstall controls which users are allowed to modify the Oracle software. Software modification includes installs, upgrades, and patching. To perform the commands that follow (as well as some that precede this), log in to the Linux computer as a Linux super user (root). To create the groups, type this: These commands have no output if the groups add successfully. Do not add any users to Linux groups unless they’re approved database administrators. Members of these groups can see almost any data they want or damage the database and Oracle installation. Creating the Oracle Software Owner On a Linux installation of Oracle, it is best practice to create a special user to own the Oracle software. While you can name the user whatever you want, best practices show that user is typically called oracle or some name with ora in it (such as ora11g). The following command creates ✓ A user called oracle ✓ With the primary group oinstall 371 Appendix A: Quick Start Install of Oracle 11g on Linux ✓ The secondary group dba ✓ With a home directory /home/oracle ✓ Korn shell as the default shell useradd –c “Oracle Software Owner” –d /home/oracle –m –g oinstall –s /usr/bin/ksh –G dba oracle After you create this user, change its password to something that you will remember. To change the password for the user oracle, type this: It prompts you for the new password. Configuring the Linux Kernel Parameters The Linux operating system has a set of kernel parameters that control how memory and processes function on the system. Installing Oracle typically involves adjusting these parameters. The parameters are found in the /etc directory in a file called sysctl.conf. Edit the sysctl.conf file and modify the following parameters to have the specified values: fs.file-max = 512 * PROCESSES # Processes should be to the total number of # sessions you expect to have on your system * 20%. kernel.shmall = 2097152 kernel.shmmax = 2147483648 # This parameter is typically set to the same size as # the memory (RAM) you have on your system in bytes) kernel.shmmni = 4096 kernel.sem = 250 32000 100 128 net.ipv4.ip_local_port_range = 1024 65000 net.core.rmem_default = 4194304 net.core.rmem_max = 4194304 net.core.wmem_default = 262144 net.core.wmem_max = 262144 net.ipv4.tcp_wmem = 262144 262144 262144 net.ipv4.tcp_rmem = 4194304 4194304 4194304 If one of the parameters doesn’t exist, add it just as it looks here. To make the changes take effect, type the following command: /sbin/sysctl –p 372 Oracle 11g For Dummies Creating the ORACLE_BASE directory The ORACLE_BASE directory serves as the starting point for all your Oracle installation files. Choosing this directory carefully is important. Ideally, it will be on its own drive or mount point. A typical ORACLE_BASE might be /u01/app/oracle. 1. Create the ORACLE_BASE directory: mkdir /u01/app/oracle 2. Change the ownership of the directory so the owner is Oracle and the group is oinstall: chown -R oracle:oinstall /u01/app/oracle 3. Change the permissions on the directory: chmod -R 775 /u01/app/oracle Now the owner can read, write, and execute; all other users can read and execute recursively. Configuring the Oracle user’s environment When you create the user oracle, the user has the korn shell. The korn shell is controlled by a .profile file in the user’s home directory. To set up the user oracle’s environment follow these steps: 1. Log in to an OS terminal window as the user oracle. You are in the home directory /home/oracle. 2. Edit the file .profile and add the following lines. export PATH=/usr/kerberos/sbin:/usr/kerberos/bin: /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:. export ORACLE_BASE=/u01/app/oracle export ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 export ORACLE_SID=dev11g export LD_LIBRARY_PATH=$ORACLE_HOME/lib export PATH=$ORACLE_HOME/bin:$PATH If the file already exists, make sure to add the lines to the bottom of the file. 3. Save and exit the .profile file. 4. Run the following command to make the changes take effect: <. .profile> There is no output. 373 Appendix A: Quick Start Install of Oracle 11g on Linux 5. See if the changes worked: You should see something like this: ORACLE_SID=dev11g ORACLE_BASE=/u01/app/oracle ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 Congratulations! You are ready to install the software. Installing the Oracle 11g database software The following steps walk you through a quick start installation of the Oracle 11g database software. The steps at this point are almost identical across all operating systems so your skills will translate very easily from OS to OS. 1. Download the software from the Oracle web site at http://technet. oracle.com. You can order it from the Oracle store. We recommend downloading it because it’s free and the same stuff you would get from the store. You can always burn it to DVD later on. 2. Copy the entire disk to the hard drive. 3. Create a directory to hold the software. Choose something like one of these: • /u01/app/oracle/stage • /u01/app/oracle/software/stage If you downloaded the software, unzip it first into the directory you created. After unzipping, you should see a folder called database. 4. Open a terminal window and go to the software directory. 5. cd into the database directory and execute the runInstaller program: <./runInstaller> It might take a minute or two depending on your machine speed. You’re welcomed by the screen shown in Figure A-1. 6. Select the Basic Installation radio button. 7. Choose an Oracle base directory. We chose /u01/app/oracle. This directory serves as the base of the Oracle installation. It also corresponds with the examples in Oracle’s official documentation, as well as the OFA standards. See Appendix B for an overview of the OFA standards. 374 Oracle 11g For Dummies Figure A-1: The Oracle Universal Installer screen welcomes you. 8. Choose an Oracle Home directory. All the Oracle executables are installed here. It should be a subdirectory of the Oracle Base. The location we chose is consistent with the OFA. 9. Select Enterprise Edition. This ensures you have all the features in this book. 10. Decide whether you want to create a starter database. We recommend not creating a starter database when you’re first install- ing the database. Isn’t getting the software installed a big enough milestone? After you make sure the software installed correctly, go to Chapter 4 and create the database yourself. This gives you more control and the opportunity to understand the database creation process. If you let the installer do it, many of the steps are left behind the scenes. 11. Click the Next button. The prerequisite checks are initiated. If you’re on a typical desktop or laptop (non-server), you might see the warning shown in Figure A-2. This tells you that the IP address is DHCP. 12. For testing, choose the check box next to the warning. In a production environment, you should have a dedicated IP address. 375 Appendix A: Quick Start Install of Oracle 11g on Linux Figure A-2: You might see this warning for DHCP. 13. Click the Install on a Summary Screen button. A screen shows the progress and a slideshow tells you about all the great features you’ll soon have at your fingertips. Depending on your machine’s speed, the install can take anywhere from five minutes to one hour. When installation is complete, you should see a window telling you so. 14. Click the Exit button to close the installer. 376 Oracle 11g For Dummies Index • Symbols and Numerics • \ back slash, 2 event 10046, 262–267 40-percent rule, 218 / forward slash, 2 10gAS (Application Server), 46 • A • Active Session History (ASH), 258–259 ADDM (Automatic Database Diagnostic Monitor), 252–255 ad-hoc queries, minimizing, 364 adump directory, 52 Agent software, 335 alert directory, 52 alert log, 288–290 ALL_viewname view, 121 ALTER privilege, 194 ALTER SYSTEM privilege, 193 ALTER USER privilege, 193 American National Standards Institute (ANSI), 112 ANALYZE command, 221–223 APPEND text command, 116 applications supported by Oracle, 9–10 .ARC extension, 35 .ARCH extension, 35 architecture Data Guard architecture, 342–349 fi les and structures, 14–15 memory, 14 processes, 14 RAC (Real Application Clusters) architecture, 330–335 archive log backup copies parameter (RMAN), 155 archive log fi les backup of, 170–171 described, 35 in Flash Recovery Area, 163–164 recovering, 151 archiving enabling, 161 Flash recovery area, storing archive logs in, 160 LOG_ARCHIVE_DEST_n initialization parameter, storing archive logs in, 160 logs fi les from, 160–161 overview, 158–159 turned off, 159 turned on, 159 ARCn process, 27 ASH (Active Session History), 258–259 ASM (Automatic Storage Management), 58, 182 ASM software, 335 audit logs, monitoring, 228 audit trail, 199 audit_fi le_dest parameter, 72 auditing default audits, 202–203 disabling, 202 enabling, 202 objects, 204–205 options for, 199 overview, 198–199 preparation for, 199–202 successful commands, 203–204 system privileges, 202–204 turning off, 207–208 unsuccessful commands, 203 verifying audits, 205–206 viewing audit information, 207 audit_trail parameter, 72 authentication operating system, 190–191 overview, 185 password, 187–190 user, 186 autoextensible data fi les, 215 378 Oracle 11g For Dummies Automatic Database Diagnostic Monitor (ADDM), 252–255 Automatic Diagnostic Repository (ADR), 73, 286–287 Automatic Memory Management, 24–26, 246 Automatic Storage Management (ASM), 58, 182 Automatic Workload Repository (AWR) Database Control method for changing snapshots, 250–251 overview, 247–248 snapshots, 247 SQL*Plus method for changing snapshots, 248–250 • B • \ back slash, 2 background processes ARCn process, 27 CJQ0 process, 27 CKPT process, 27 DBWn process, 27 DIA0 process, 27 J000 process, 27 LGWR process, 27 overview, 26–28 PMON process, 27 SMON process, 27 VKTM process, 27 backup optimization parameter (RMAN), 155 backup sets compressing backups, 167 copies compared, 164 database, backing up entire, 166–167 hot backups, 165 incremental backups, 167–169 naming backups, 167 overview, 164 tablespace, backing up, 167 tablespaces, backing up multiple, 167 what to backup, 165–166 backups. See also Recovery Manager (RMAN) after installation, 360 archive logs, recovering, 151 consistent, 159 control fi les, recovering, 150 corruption, protection against, 151 data fi les, recovering, 150 DBA checking, 226–227 dropped objects, protection against, 150 errors, checking backup log for, 227 instance failure, protection against, 149 media failure, protection against, 150–151 Oracle code tree, protection against losing fi les in, 150 parameter fi les, recovering, 151 requirements for installation, 60 script for, 226–227 usability of, 227 user error, protection against, 152 viewing, 171–173 basic database checks, performing, 278–280 batch jobs, checking, 227 BEGIN keyword, 126 bit mapped indexes, 141 bit version, using correct, 356 block change tracking, 168–169 block size, choosing, 82 block structure, 126–127 block write triggers, 21 blocks, 41 B–Tree indexes, 141 buffer, 19, 115 built-in constraints, using, 361–362 • C • cdump directory, 52 central storage, 333 centralized management, confi guring for, 78 chain (dependency) jobs, 229 CHANGE/old/new command, 116 character set, choosing, 82–83 check constraints, 362 checking database after creation, 87 checkpoint, 21 CJQ0 process, 27 CKPT process, 27 CLEAR BUFFER command, 116 client, 112 client-server applications, 44–45 379379 Index cloning an existing database, 74 cluster awareness, 338 Cluster Control (crsctl), 339–341 cluster interconnect, 333–334 clustering, 14 clustering software, 335 code stored in database, using, 365–366 code tree, protection against losing fi les in, 150 Commercial Off The Shelf (COTS) applications, 48 communication fl ow, 100–101 compatible parameter, 72 complete recovery with Data Recovery Advisor (DRA), 175–178 for one or more control fi les, 177–178 for one or more data fi les, 175–177 overview, 175 without Data Recovery Advisor (DRA), 178–180 component confi gurations, 48–49 compressing backups, 167 compression algorithm parameter (RMAN), 156 COMPRESSION parameter (Data Pump Export), 236 .CON extension, 32 confi guration for centralized management, 78 fl ashback database, 318 instances, 70–73 kernel parameters, 371 profi les, 355 quick start install of Oracle 11g on Linux, 372–373 Recovery Manager (RMAN), 153–156 CONNECT role, 197 CONNECT user command, 116 connecting to the database instance communication fl ow, 100–101 database listener, starting, 105 database listener, stopping, 106 listener.ora fi le, setting up, 102–104 local (bequeath) connection, 100 overview, 99–100 remote connection, 100 testing the connection, 107–108 tnsnames.ora fi le, setting up, 101–102 troubleshooting, 108–109 connection pool, 47 consistent backups, 159 constraints, 141 CONTENT parameter Data Pump Export, 236 Data Pump Import, 238 control fi le autobackup format parameter (RMAN), 155 control fi le autobackup parameter (RMAN), 155 control fi les complete recovery for one or more control fi les, 177–178 overview, 32–33 recovering, 150 control_fi les parameter, 72 copies backup sets compared, 164 of entire database, 169 overview, 164, 169–170 of tablespace, 169 used to recover database, 182–184 corruption, protection against, 151 CPU speed, 54 CPU utilization, 275–276 CREATE ANY TABLE privilege, 193 CREATE JOB privilege, 193 CREATE SESSION privilege, 192 CREATE SYNONYM privilege, 193 CREATE TABLESPACE privilege, 193 creating a database. See also Database Confi guration Assistant (DBCA) checking database after creation, 87 cloning an existing database, 74 with combination of SQL commands and DBCA, 74 with DBCA, 74 manually with SQL commands, 74 memory settings, 86 methods for, 74 overview, 74 crsctl (Cluster Control), 339–341 .CTL extension, 32 cumulative backups, 168 cursors, 125 380 Oracle 11g For Dummies • D • dark fi ber, 341 Data Control Language (DCL), 120 Data Defi nition Language (DDL), 21, 120 Data Dictionary ALL_viewname view, 121 DBA_viewname view, 121 describe (desc) command, 122 described, 121 join, creating a, 123–125 list (l) command, 123 USER_viewname view, 121 views, 121 V$_viewname view, 121 data fi le backup copies parameter (RMAN), 155 data fi les complete recovery for one or more data fi les, 175–177 overview, 31–32, 124 recovering, 150 Data Guard architecture failovers, 348 logical standby database, 347 maximum availability protection mode, 344 maximum performance protection mode, 344 maximum protection protection mode, 344 overview, 342–344 physical standby database, 344–347 switchovers, 348–349 Data Manipulation Language (DML), 45, 120 data normalization, 363 Data Pump directories, creating, 239–240 dump fi le, 234 log fi le, 234 overview, 234–235 parfi le, 234 Data Pump Export COMPRESSION parameter, 236 CONTENT parameter, 236 DIRECTORY parameter, 236 DUMPFILE parameter, 236–237 ESTIMATE parameter, 237 EXCLUDE parameter, 237 FILESIZE parameter, 237 FLASHBACK_TIME parameter, 237 INCLUDE parameter, 237 launching, 235–236 NETWORK_LINK parameter, 237 PARALLEL parameter, 237 parameter fi le used with, 240–242 SCHEMAS parameter, 237 TABLES parameter, 237 TABLESPACES parameter, 237 Data Pump Import CONTENT parameter, 238 DIRECTORY parameter, 238 DUMPFILE parameter, 238 ESTIMATE parameter, 238 EXCLUDE parameter, 239 FLASHBACK_SCN parameter, 239 FLASHBACK_TIME parameter, 239 INCLUDE parameter, 239 NETWORK_LINK parameter, 239 overview, 238–239 PARALLEL parameter, 239 REMAP_SCHEMA parameter, 239 REMAP_TABLESPACE parameter, 239 SCHEMAS parameter, 239 TABLES parameter, 239 TABLESPACES parameter, 239 Data Query Language (DQL), 119 Data Recovery Advisor (DRA), 175–178 database. See also creating a database; populating the database backing up entire database, 166–167 defi ned, 92 described, 13 instances compared, 13–14 overview, 13–14 performance tuning, 246–247 database administrator. See DBA (database administrator) database block, 19 database buffer cache block write triggers, 21 dirty blocks, 20 free blocks, 20 overview, 18–19 state of, 19–20 Database Confi guration Assistant (DBCA) block size, choosing, 82 centralized management, confi guring for, 78 381381 Index character set, choosing, 82–83 cluster awareness, 338 connection mode, choosing, 83 described, 63 exiting, 85 global database name fi eld, 77 launching, 74 local management, confi guring for, 78 location for fi le storage, choosing, 79, 80 overview, 74–75 passwords, 79 security options, 83–84 SID fi eld, 77 steps used in, 75–85 system for fi le storage, choosing, 79 used to confi gure Enterprise Manager (EM), 302–303 Database Control creating users with, 303–304 main page, 311–313 metrics, working with, 305–307 monitoring database with, 305–307 notifi cations, setting up, 307–308 overview, 301 policies, working with, 305–307 removing users with, 304 targets, 305, 311–313 user notifi cations, setting up, 308–310 database instance, 13. See also connecting to the database instance database jobs (Scheduler), 229 database link, 143 database listener starting, 105 stopping, 106 database parameter fi le, 91–92 Database Replay overview, 324–325 replaying the workload, 326–328 using, 325–326 database scripts, 296–297 DBA (database administrator) audit logs, monitoring, 228 backups, checking, 226–227 batch jobs, checking, 227 described, 211 Enterprise Manager used to check space available, 213–214 login abuse, fi nding, 225 segments, monitoring space in, 216–217 space available, monitoring, 212–216 SQL queries used to check space available, 214–216 stale sessions, fi nding, 224–225 system logs, monitoring, 228 tables that grow and shrink, monitoring, 217–223 users, monitoring, 223–227 dba group creating, 370 described, 64 DBA role limiting number of people having, 365 overview, 197 DBA_viewname view, 121 DB_BLOCK_SIZE parameter, 246 db_block_size parameter, 72 DBCA. See Database Confi guration Assistant db_domain parameter, 72 .DBF extension, 31 DB_FILE_MULTIBLOCK_READ_COUNT parameter, 247 db_name parameter, 73 db_recovery_fi le_dest parameter, 73 db_recovery_fi le_dest_size parameter, 73 DBWn process, 27 DCL (Data Control Language), 120 DDL (Data Defi nition Language), 21, 120 Decision Support System (DSS), 10 DECLARE keyword, 126 dedicated server, 104 dedicated server process, 29 default audits, 202–203 default device type parameter (RMAN), 155 DEFAULT profi le, 189–190 DEFAULT tablespace, 137 DEL command, 116 DEL LAST command, 116 DEL n command, 116 DELETE privilege, 194 dependency-based jobs (Scheduler), 229 describe (desc) command, 122 design tips ad-hoc queries, minimizing, 364 built-in constraints, using, 361–362 code stored in database, using, 365–366 data normalization, 363 382 Oracle 11g For Dummies design tips (continued) DBA role, limiting number of people having, 365 fi le storage, rules for, 362–363 naming conventions, using, 363 password security, enforcing, 364–365 privileges, proper setup of, 364 recovery, testing your strategy for, 366 roles, proper setup of, 364 detached jobs (Scheduler), 229 DIA0 process, 27 diagnostic utilities database scripts, 296–297 Enterprise Manager (EM), 292–294 overview, 292 Remote Diagnostic Agent (RDA), 294–296 diagnostic_dest parameter, 73 dictionary cache, 17 differential backups, 168 directory adump, 52 alert, 52 cdump, 52 creating, 239–240 dpdump, 52 incident, 52 installation requirements, 50–53 pfi le, 52 trace, 52 wallet, 52 DIRECTORY parameter Data Pump Export, 236 Data Pump Import, 238 dirty blocks, 20 disk, 54 disk space, availability of, 276–277 DML (Data Manipulation Language), 45, 120 dpdump directory, 52 DQL (Data Query Language), 119 DRA (Data Recovery Advisor), 175–178 DROP ANY TABLE privilege, 193 DROP USER privilege, 193 dropped objects, protection against, 150 DSS (Decision Support System), 10 dump fi le Data Pump, 234 troubleshooting with database logs, 291 DUMPFILE parameter Data Pump Export, 236–237 Data Pump Import, 238 dynamic performance views, 121 • E • EDIT command, 116 EDIT fi lename command, 116 encryption, 208–209 encryption algorithm parameter (RMAN), 155 encryption for database parameter (RMAN), 155 END keyword, 126 Enterprise Backup Utility (EBU), 152 Enterprise Manager (EM). See also Database Control Database Confi guration Assistant (DBCA) used to confi gure, 302–303 Grid Control, 301–302 Java Console, 300–301 overview, 8, 292–294 Segment Advisor, 219–221 used for creating objects, 144–146 used to check space available, 213–214 entire database, copies of, 169 environment for owner, confi guring, 372–373 environment variables ORACLE_BASE directory, 66 ORACLE_HOME directory, 66–67 ORACLE_SID directory, 67 overview, 65 PATH variable, 67 setting up, 90–91 environmental requirements database parameter fi le, 91–92 logging in as DBA account, 90 logging in to database server, 90 overview, 90 starting SQL*Plus as a DBA, 91 error code, 227 error messages analyzing, 281–283 example of, 282 oerr utility used to get information on, 282–283 383383 Index errors, checking backup log for, 227 ESTIMATE parameter Data Pump Export, 237 Data Pump Import, 238 event 10046, 262–267 event-based jobs (Scheduler), 229 EXCEPTION keyword, 126 EXCLUDE parameter Data Pump Export, 237 Data Pump Import, 239 EXECUTE privilege, 194 EXIT command, 116 EXP_FULL_DATABASE/IMP_FULL_ DATABASE role, 197 explain plan, 256–258 Extended RAC, 341 Extensible Markup Language (XML), 9 extents, 40, 131 external identifi cation, 191 external jobs (Scheduler), 229 • F • failovers, 348 fallback plan if solution fails, 285 familiarizing yourself with the Oracle environment, 63–64 fi le system, 58 fi les. See also PFILE (parameter fi le) archive log, 35, 151, 163–164, 170–171 control, 32–33, 150, 177–178 data, 31–32, 124, 150, 175–177 overview, 14–15, 30 redo log, 33–34 server parameter fi le (SPFILE), 36–37, 70–71 storage, rules for, 362–363 tempfi le, 31 FILESIZE parameter (Data Pump Export), 237 Flash Recovery Area (FRA) archive log fi les in, 163–164 enabling, 161–162 overview, 73, 80 storing archive logs in, 160 FLASHBACK ARCHIVE privilege, 193 fl ashback data archive, 322–324 fl ashback database confi guring, 318 enabling, 319 overview, 317–318 procedure for fl ashing back, 321–322 reasons for using, 319 restore points, using, 320 fl ashback logs, 318 FLASHBACK_SCN parameter (Data Pump Import), 239 FLASHBACK_TIME parameter Data Pump Export, 237 Data Pump Import, 239 foreign keys, 141, 361 40-percent rule, 218 / forward slash, 2 fragmentation, 40 free blocks, 20 function, 142 function-based indexes, 141 • G • GET fi lename command, 116 global database name fi eld (DBCA), 77 glogin.sql script, 114–115 GRANT ANY OBJECT privilege, 193 granting, 195–196 grid computing, 8 Grid Control, 301–302 group ID numbers, assigning, 359 groups, creating, 370 • H • hard drive, installation from, 357–358 hardware CPU speed, 54 disk, 54 installation, 53–54 memory, 53 minimum, 54 overview, 53–54 performance tuning, 244 RAC (Real Application Clusters) architecture, 331–334 virtual memory, 54 384 Oracle 11g For Dummies header, 142 heap area, 19 hierarchical data model, 7 high-availability architecture Data Guard architecture, 342–349 overview, 329 RAC (Real Application Clusters) architecture, 330–342 hot backups, 165 HTTP (HyperText Transfer Protocol), 46 hybrid databases, 10 • I • incident directory, 52 INCLUDE parameter Data Pump Export, 237 Data Pump Import, 239 incomplete recovery, 180–182 incremental backups block change tracking, 168–169 cumulative backups, 168 differential backups, 168 overview, 167 when to use, 168 index bit mapped, 141 B–Tree, 141 function-based, 141 overview, 141 INDEX privilege, 194 INPUT command, 116 INSERT privilege, 194 installation. See also quick start install of Oracle 11g on Linux application requirements, 60 backups after, 360 backups requirements, 60 bit version, using correct, 356 directory requirements, 50–53 group ID numbers, assigning, 359 from hard drive, 357–358 hardware requirements, 53–54 for multiple versions of Oracle, 50 network connectivity requirements, 59 of new version in parallel with existing one, 65 optimal fl exible architecture (OFA), implementing, 354 oracle, installation by user named, 357 Oracle patches requirements, 59 overview, 49–50 patchsets, updating, 358–359 profi le, confi guring your, 355 of RAC (Real Application Clusters) architecture, 336–342 reading documentation before, 353–354 security requirements, 60 software requirements, 55–56 storage requirements, 56–58 switching between different Oracle installations on the same machine, 68–69 umask setting, 356 user ID numbers, assigning, 359 user requirements, 50 version requirements, 58–59 instances confi guring, 70–73 defi ned, 92 described, 13 failure, protection against, 149 overview, 13–14 starting, 92–96 Integrated Development Environment (IDE), 9 internal drives, 56 I/O cost, 35 • J • J000 process, 27 Java, 9 Java Console, 300–301 Java pool, 23 Java Virtual Machine (JVM), 23, 46 jobs in Scheduler, 229 join, creating a, 123–125 • K • kernel parameters, confi guring, 371 kernel version, checking your, 368–369 385385 Index • L • large pool, 22 LDAP (Lightweight Directory Access Protocol), 48–49 Least Recently Used (LRU) algorithm, 17, 18 LGWR process, 27 library cache, 16–17 lightweight jobs (Scheduler), 229 Linux minimum hardware requirements, 54 Oracle software owner, 64 LIST command, 116, 171–173 LIST n command, 116 listener log, 291–292 listener.ora fi le, setting up, 102–104 local (bequeath) connection, 100 local management, confi guring for, 78 LOG command, 226 .LOG extension, 33, 35 log fi les from archiving, 160–161 Data Pump, 234 log switch operation, 33–34 Log Writer (LGWR), 33 LOG_ARCHIVE_DEST_n initialization parameter, storing archive logs in, 160 LOG_BUFFER parameter, 247 logging in as DBA account, 90 logging in to database server, 90 logical standby database, 347 logical structures applying, 37–41 extents, 40 Oracle blocks, 41 overview, 37 segments, 39 tablespaces, 38–39 login abuse, fi nding, 225 login.sql script, 114–115 LRU (Least Recently Used) algorithm, 17, 18 lsnrctl start command, 105 lsnrctl status command, 106–107 lsnrctl stop command, 106 • M • manually creating a database with SQL commands, 74 MAXSETSIZE parameter (RMAN), 155 mean time to recovery (MTTR), 175 media failure, protection against backups, 150–151 Recovery Manager (RMAN), 173 member, 34 memory hardware requirements, 53 overview, 14 settings for creating a database, 86 sharing, 86 troubleshooting with system methodology, 276 memory management automatic, 24–26 overview, 24 memory structures, 15 MEMORY_MAX_TARGET=nM parameter, 246 memory_target parameter, 73 MEMORY_TARGET=nM parameter, 246 metadata, 121 metrics, working with, 305–307 mirroring, 57 monitoring database with Database Control, 305–307 mount point, 2 MOUNT state, 93 MTTR (mean time to recovery), 175 multiple versions of Oracle, installation for, 50 multi-threaded servers (MTS), 104 multi-tier applications advantages of, 47 overview, 45–47 • N • naming backups, 167 conventions, 363 Net8. See Oracle Net 386 Oracle 11g For Dummies Network Confi guration Assistant (NETCA), 338 NETWORK_LINK parameter Data Pump Export, 237 Data Pump Import, 239 networks connectivity requirements for installation, 59 interfaces for RAC (Real Application Clusters) architecture, 334 troubleshooting with system methodology, 272–273 nodes, 8, 332–333 NOMOUNT state, 92 Not Null constraints, 362 notifi cations, setting up, 307–308 • O • object privileges ALTER privilege, 194 DELETE privilege, 194 described, 194–195 EXECUTE privilege, 194 granting, 195–196 INDEX privilege, 194 INSERT privilege, 194 REFERENCES privilege, 194 SELECT privilege, 194 UPDATE privilege, 194 object-oriented programming (oop), 9 objects auditing, 204–205 creating, 140–146 database link, 143 Enterprise Manager used for creating, 144–146 function, 142 index, 141 methods for creating, 143–146 package, 142 procedure, 142 scripts for creating, 143–144 synonym, 143 table, 141 trigger, 143 types of, 140–143 view, 141 OEM Database Control. See Database Control OEM Grid Control, 301–302 OEM Java Console, 300–301 oerr utility, 282–283 OID (Oracle Internet Directory), 48–49 OIFCFG (Oracle Interface Confi guration Tool), 341 oinstall group creating, 370 described, 64 one-off patches, 59 Online Analytical Processing (OLAP), 10 Online Transactional Processing (OLTP), 10 opatch utility, 59 OPEN state, 93–94 open_cursors parameter, 73 operating system authentication, 190–191 RAC (Real Application Clusters) architecture, 334–335 version, checking your, 368 OPS (Oracle Parallel Server), 331 optimal fl exible architecture (OFA), implementing, 354 OPTIMIZER_INDEX_COST_ADJ parameter, 247 Oracle advantages of, 10–11 applications supported by, 9–10 choosing, 10–11 described, 7 patches requirements, 59 Oracle Interface Confi guration Tool (OIFCFG), 341 Oracle Internet Directory (OID), 48–49 Oracle Net functionality, verifying, 279 overview, 99–100 Oracle Net Confi guration Assistant, 108 Oracle software owner creating, 370–371 fi nding, 64–65 in Linux, 64 in UNIX, 64 in Windows, 64–65 387387 Index Oracle Universal Installer (OUI) overview, 56, 337–338 switching between different Oracle installations on the same machine, 68–69 ORACLE_BASE directory, 50–51, 66, 372 ORACLE_HOME directory, 50–53, 66–67 ORACLE_SID directory, 67 Oracle-supplied roles, 197 oraenv script, 68 owner, Oracle software. See Oracle software owner • P • package body, 142 checking your, 369–370 described, 142 header, 142 spec, 142 PARALLEL parameter Data Pump Export, 237 Data Pump Import, 239 parallelism parameter (RMAN), 155 parameter fi les overview, 36–37 recovering, 151 used with Data Pump Export, 240–242 parameters, setting, 71–73 parfi le, 234 parity, 57 parsing, 16–17 partitioning, 141 password authentication creating a password profi le, 189 Database Confi guration Assistant (DBCA), 79 DEFAULT profi le, 189–190 enforcing, 364–365 overview, 187 profi les used to enforce password security, 187–188 password verify function, 188 patchsets, updating, 358–359 PATH variable, 67 performance tuning Automatic Database Diagnostic Monitor (ADDM), 252–255 Automatic Workload Repository (AWR), 247–251 database, 246–247 hardware, 244 overview, 243–244 SQL tuning, 255–267 steps for, 245 pfi le directory, 52 PFILE (parameter fi le) audit_fi le_dest parameter, 72 audit_trail parameter, 72 compatible parameter, 72 control_fi les parameter, 72 db_block_size parameter, 72 db_domain parameter, 72 db_name parameter, 73 db_recovery_fi le_dest parameter, 73 db_recovery_fi le_dest_size parameter, 73 diagnostic_dest parameter, 73 fi nding, 71 memory_target parameter, 73 open_cursors parameter, 73 parameters, setting, 71–73 processes parameter, 73 undo_tablespace parameter, 73 using, 70–71 PGA (Program Global Area), 23 PGA_AGGREGATE_TARGET parameter, 247 physical standby database, 344–347 physical structures, 30 PL/SQL advantages of, 125 block structure, 126–127 function result cache, 18 overview, 125 security, 125 PMON process, 27 policies, working with, 305–307 populating the database objects, creating, 140–146 overview, 129–130 schemas, creating, 136–140 tablespaces, creating, 130–135 users, creating, 136–140 port 1521, 103, 109 primary keys, 141, 361 private SQL area, 23 private synonym, 143 388 Oracle 11g For Dummies privileges. See also system privileges granted with roles, 196–197 object, 194–196 overview, 191 proper setup of, 364 system, 192–194 procedure, 142 processes background, 26–28 overview, 14, 26 server, 28–30 user, 28–29 processes parameter, 73 profi le confi guring, 355 password security, profi les used to enforce, 187–188 scripts, 114–115 Program Global Area (PGA), 23 programs in Scheduler, 229 public synonym, 143 • Q • quick start install of Oracle 11g on Linux dba group, creating, 370 environment for owner, confi guring, 372–373 groups, creating, 370 installing the Oracle 11g database software, 373–375 kernel parameters, confi guring, 371 kernel version, checking your, 368–369 oinstall group, creating, 370 operating system version, checking your, 368 Oracle software owner, creating the, 370–371 ORACLE_BASE directory, creating, 372 packages, checking your, 369–370 setting up the operating system, 367 users, creating, 370 quickest result cache, 17–18 QUIT command, 116 • R • RAC (Real Application Clusters) architecture Agent software, 335 ASM software, 335 central storage, 333 cluster interconnect, 333–334 clustering software, 335 hardware considerations for, 331–334 installation of, 336–342 network interfaces, 334 nodes, 332–333 operating system, 334–335 OPS (Oracle Parallel Server) compared, 331 optional software, 335 Oracle database software, 335 overview, 8, 330–331 software considerations for, 334–335 RAID levels, 57 Random Access Memory (RAM), 53 raw devices, 58 raw fi les, 208 .RDO extension, 33 reading documentation before installation, 353–354 recovery, testing your strategy for, 366 Recovery Manager (RMAN) archive log backup copies parameter, 155 archive logs, backup of, 170–171 backup optimization parameter, 155 backup sets, 164–169 complete recovery, 175–180 compression algorithm parameter, 156 confi guring, 153–156 control fi le autobackup format parameter, 155 control fi le autobackup parameter, 155 copies, 164, 169–170 copies used to recover database, 182–184 data fi le backup copies parameter, 155 default device type parameter, 155 encryption algorithm parameter, 155 encryption for database parameter, 155 389389 Index incomplete recovery, 180–182 MAXSETSIZE parameter, 155 media failure, protection against, 173 overview, 152 parallelism parameter, 155 recovery catalog, 156–158 retention policy parameter, 154–155 snapshot control fi le name parameter, 156 starting, 152–153 types of recoveries with, 173–174 user error, protection against, 173 verifying the problem, 174–175 RECOVERY_CATALOG_OWNER role, 197 redo entry, 21 redo log buffer, 21–22 redo log fi les, 33–34 REFERENCES privilege, 194 referential integrity, 361 relational model, 7 REMAP_SCHEMA parameter (Data Pump Import), 239 REMAP_TABLESPACE parameter (Data Pump Import), 239 remote connection, 100 Remote Diagnostic Agent (RDA), 294–296 replaying the workload, 326–328 researching solutions, 283–284 RESOURCE role, 197 restore points, using, 320 RESTRICTED SESSION mode, 95–96 RESUMABLE privilege, 193 retention policy parameter (RMAN), 154–155 roles CONNECT role, 197 DBA role, 197 EXP_FULL_DATABASE/IMP_FULL_ DATABASE role, 197 Oracle-supplied roles, 197 overview, 196–197 privileges granted with, 196–197 proper setup of, 364 RECOVERY_CATALOG_OWNER role, 197 RESOURCE role, 197 SCHEDULER_ADMIN role, 197 SYSDBA role, 198 rolling forward, 35 rows, 141 rows migration, 218 rule sets, 310 running, verify that database is, 278 • S • SAN (storage area networks), 182 SAVE fi lename command, 116 Scheduler chain (dependency) jobs, 229 creating a job, 230–233 database jobs, 229 dependency-based jobs, 229 detached jobs, 229 disabling a job, 233 event-based jobs, 229 external jobs, 229 jobs, 229 lightweight jobs, 229 overview, 228–229 programs, 229 removing a job, 233–234 schedules, 229 time-based jobs, 229 windows, 229 SCHEDULER_ADMIN role, 197 schedules, 229 schemas, creating, 136–140 SCHEMAS parameter Data Pump Export, 237 Data Pump Import, 239 scripts for backups, 226–227 for creating objects, 143–144 security. See also password authentication auditing, 198–208 authentication, 185–191 encryption, 208–209 installation requirements, 60 options in Database Confi guration Assistant (DBCA), 83–84 PL/SQL, 125 privileges, 191–196 roles, 196–198 Virtual Private Database (VPD), 198 Segment Advisor, 219–221 390 Oracle 11g For Dummies segments described, 39, 124, 131 monitoring space in, 216–217 SELECT privilege, 194 server, 112 Server Control (srvctl), 338–339 server parameter fi le (SPFILE), 36–37, 70–71 server processes dedicated, 29 overview, 28–29 shared, 29–30 server utilization, 273–275 session, establishing a database, 279–280 session memory, 23 SET command, 116 SGA (System Global Area) components of, 15–16 database buffer cache, 18–21 Java pool, 23 large pool, 22 overview, 15–16, 73 redo log buffer, 21–22 shared pool, 16–18 SGA_TARGET parameter, 247 shared pool dictionary cache, 17 Least Recently Used (LRU) algorithm, 17, 18 library cache, 16–17 overview, 16 quickest result cache, 17–18 shared server process, 29–30 shared servers, 104 sharing memory, 86 SHUTDOWN ABORT method, 98, 99 SHUTDOWN IMMEDIATE method, 98 SHUTDOWN method, 97, 98 SHUTDOWN TRANSACTIONAL method, 97–98, 99 SID fi eld (DBCA), 77 SMON process, 27 snapshot control fi le name parameter (RMAN), 156 snapshots, 247 SOA (Service Oriented Architecture), 9 software owner, Oracle. See Oracle software owner space available checking for, 214–216 monitoring, 212–216 spec, 142 SPFILE (server parameter fi le), 36–37, 70–71 SPOOL command, 116 SQL Access Advisor, 259 SQL Navigator (Quest Software), 146 SQL Profi ling and Plan Management, 260–261 SQL (Structured Query Language) overview, 111–112 queries used to check space available, 214–216 result cache, 17–18 SQL tuning Active Session History (ASH), 258–259 event 10046, 262–267 explain plan, 256–258 overview, 255–256 SQL Tuning Advisor, 259–260 SQL*Net. See Oracle Net sqlnet.ora fi le, 104 SQL*Plus buffer, 115 changing snapshots, 248–250 command-line help, 118–119 commands, 115–117 executing, 113–114 glogin.sql script, 114–115 language elements, 119–120 login.sql script, 114–115 overview, 112–113 profi le scripts, 114–115 space available, checking for, 214–216 users, creating, 137–138 srvctl (Server Control), 338–339 stale sessions, fi nding, 224–225 START command, 116 START fi lename command, 116 STARTUP command, 96 state of database buffer cache, 19–20 stopping the database choosing method for, 98–99 methods for, 97–98 overview, 96–97 SHUTDOWN, 97, 98 391391 Index SHUTDOWN ABORT, 98, 99 SHUTDOWN IMMEDIATE, 98 SHUTDOWN TRANSACTIONAL, 97–98, 99 storage Automatic Storage Management (ASM), 58 cost, 35 fi le system, 58 installation requirements, 56–58 raw devices, 58 storage area networks (SAN), 182 storage arrays, 56–57 striping, 57 successful commands, auditing, 203–204 switching between different Oracle installations on the same machine, 68–69 switchovers, 348–349 synonym, 143 SYSAUX tablespace, 38 SYSDBA role, 198 system checks, performing basic, 272–277 system event logs, 277 system for fi le storage, choosing, 79 System Global Area. See SGA (System Global Area) system logs, monitoring, 228 system privileges ALTER SYSTEM privilege, 193 ALTER USER privilege, 193 auditing, 202–204 CREATE ANY TABLE privilege, 193 CREATE JOB privilege, 193 CREATE SESSION privilege, 192 CREATE SYNONYM privilege, 193 CREATE TABLESPACE privilege, 193 DROP ANY TABLE privilege, 193 DROP USER privilege, 193 FLASHBACK ARCHIVE privilege, 193 GRANT ANY OBJECT privilege, 193 RESUMABLE privilege, 193 SYSTEM tablespace, 38 • T • tables described, 141 foreign keys in, 141 primary keys in, 141 rows in, 141 that grow and shrink, monitoring, 217–223 TABLES parameter Data Pump Export, 237 Data Pump Import, 239 tablespaces backing up, 167 backing up multiple, 167 copies of, 169 creating, 130–135 DEFAULT tablespace, 137 described, 124 overview, 38–39 SYSAUX tablespace, 38 SYSTEM tablespace, 38 TEMP tablespace, 38 TEMPORARY tablespace, 137 UNDO tablespace, 38 TABLESPACES parameter Data Pump Export, 237 Data Pump Import, 239 targets, 8, 305, 311–313 TEMP tablespace, 38 tempfi le, 31 TEMPORARY tablespace, 137 10gAS (Application Server), 46 testing the connection, 107–108 time-based jobs (Scheduler), 229 TKPROF tool, 266–267 tnsnames.ora fi le setting up, 101–102 troubleshooting, 109 tnsping utility, 107–108 TOAD (Quest Software), 146 trace directory, 52 trace event 10046, 262–267 trace fi le, 290–291 Transaction Control Language (TCL), 120 trigger, 143 troubleshooting with database logs alert log, 288–290 Automatic Diagnostic Repository (ADR), 286–287 dump fi le, 291 listener log, 291–292 overview, 286–288 trace fi le, 290–291 392 Oracle 11g For Dummies troubleshooting with system methodology basic database checks, performing, 278–280 CPU utilization, 275–276 disk space, availability of, 276–277 error messages, analyzing, 281–283 fallback plan if solution fails, 285 identifying the real problem, 270–271 memory, 276 networks, 272–273 Oracle NET functionality, verifying, 279 overview, 270 planning solution, 284 ramifi cations of solution, 284 researching solution, 283–284 running, verify that database is, 278 server utilization, 273–275 session, establishing a database, 279–280 solution, developing and applying a, 283–286 support for solution, 285 system checks, performing basic, 272–277 system event logs, 277 testing solution, 284–285 verifi cation that solution worked, 286 two-tier applications, 44–45 • U • umask setting, 356 UNDO tablespace, 38 undo_tablespace parameter, 73 unique constraints, 362 unsuccessful commands, auditing, 203 unused row space, de-allocating, 219–221 UPDATE privilege, 194 used extent, 216 user error, protection against backups, 152 Recovery Manager (RMAN), 173 user processes, 28–29 users authentication, 186 creating, 136–140, 370 creating users with Database Control, 303–304 ID numbers, assigning, 359 installation requirements, 50 monitoring, 223–227 notifi cations, setting up, 308–310 USER_viewname view, 121 • V • verifying audits, 205–206 versions installation of new version in parallel with existing one, 65 installation requirements, 58–59 views, 121 virtual memory, 54 Virtual Private Database (VPD), 198 VKTM process, 27 V$_viewname view, 121 • W • wallet directory, 52 Windows minimum hardware requirements, 54 Oracle software owner, 64–65 • X • XML (Extensible Markup Language), 9 Chris Zeis Chris Ruel Michael Wessler Learn to: • Set up and manage an Oracle database • Maintain and protect your data • Understand Oracle database architecture • Troubleshoot your database and keep it running smoothly Oracle® 11g Making Everything Easier! ™ Open the book and find: • Two ways to manage your database • What tablespaces are and how to use them • How to automate jobs with the Oracle Scheduler • Ten common installation tips • How to use SQL in Oracle • When to use online, offline, control file, and archive log backups • Database encryption options • Advantages of the Flashback database Chris Zeis is Chief Technology Officer and partner at Perpetual Technologies, Inc., an Oracle partner. Chris Ruel is an Oracle database administrator and consultant. Michael Wessler manages multiple Web applications for the Department of Defense and consults at various government and private agencies. $29.99 US / $32.99 CN / £19.99 UK ISBN 978-0-470-27765-2 Database Management/General Go to dummies.com® for more! Grow wise about Oracle and get going with the leading database software! Are you a seasoned system administrator charged with setting up an Oracle database? Or did you suddenly become a DBA by default? Either way, this book will guide you through the mysteries of Oracle and database administration. Here are the nuts and bolts of creating an Oracle database, implementing it, and keeping it running in tiptop form. • Build it — learn the building blocks behind the database engine and understand Oracle’s physical and logical structures • Prepare for takeoff — review the hardware, software, system, and storage requirements for implementation • Know your environment — recognize and accommodate the differences between Oracle installations on Windows and on Linux/UNIX • Defend it — assess potential threats to your database, configure Oracle Recovery Manager, and create backup and recovery procedures • Maintain it — know the daily and intermittent tasks necessary to keep your database running properly • Head off trouble — implement the system troubleshooting methodology, use Oracle database logs, and explore other diagnostic utilities • Manage it — monitor with Oracle Enterprise Manager Oracle ® 11g Zeis Ruel Wessler Spine: .816
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