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www.sybex.com OCP: Oracle9i™ Performance Tuning Study Guide Joseph C Johnson San Francisco London Copyright â2002 SYBEX, Inc., Alameda, CA www.sybex.com Associate Publisher: Neil Edde Acquisition and Developmental Editor: Jeff Kellum Editor: Linda Stephenson Production Editor: Leslie E H Light Technical Editors: Robert Bryla and Ashok Hanumanth Book Designer: Bill Gibson Graphic Illustrator: Tony Jonick Electronic Publishing Specialist: Interactive Composition Corporation Proofreaders: Nanette Duffy, Emily Hsuan, and Nancy Riddiough Indexer: Ron Strauss CD Coordinator: Dan Mummert CD Technician: Kevin Ly Cover Designer: Archer Design Cover Photographer: Photo Researchers Copyright © 2002 SYBEX Inc., 1151 Marina Village Parkway, Alameda, CA 94501 World rights reserved No part of this publication may be stored in a retrieval system, transmitted, or reproduced in any way, including but not limited to photocopy, photograph, magnetic, or other record, without the prior agreement and written permission of the publisher Library of Congress Card Number: 2002102009 ISBN: 0-7821-4065-3 SYBEX and the SYBEX logo are either registered trademarks or trademarks of SYBEX Inc in the United States and/or other countries Screen reproductions produced with FullShot 99 FullShot 99 © 1991–1999 Inbit Incorporated All rights reserved FullShot is a trademark of Inbit Incorporated The CD interface was created using Macromedia Director, COPYRIGHT 1994, 1997–1999 Macromedia Inc For more information on Macromedia and Macromedia Director, visit http://www.macromedia.com Internet screen shot(s) using Microsoft Internet Explorer reprinted by permission from Microsoft Corporation SYBEX is an independent entity from Oracle Corporation and is not affiliated with Oracle Corporation in any manner This publication may be used in assisting students to prepare for an Oracle Certified Associate/Professional exam Neither Oracle Corporation nor SYBEX warrants that use of this publication will ensure passing the relevant exam Oracle is either a registered trademark or a trademark of Oracle Corporation in the United States and/or other countries TRADEMARKS: SYBEX has attempted throughout this book to distinguish proprietary trademarks from descriptive terms by following the capitalization style used by the manufacturer The author and publisher have made their best efforts to prepare this book, and the content is based upon final release software whenever possible Portions of the manuscript may be based upon pre-release versions supplied by software manufacturer(s) The author and the publisher make no representation or warranties of any kind with regard to the completeness or accuracy of the contents herein and accept no liability of any kind including but not limited to performance, merchantability, fitness for any particular purpose, or any losses or damages of any kind caused or alleged to be caused directly or indirectly from this book Manufactured in the United States of America 10 Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com To Our Valued Readers: In a CertCities.com article dated December 15, 2001, Oracle certification was ranked #2 in a list of the “10 Hottest Certifications for 2002.” This shouldn’t come as a surprise, especially when you consider the fact that the OCP program nearly tripled in size (from 30,000 to 80,000) in the last year Oracle continues to expand its dominance in the database market, and as companies begin integrating Oracle9i systems into their IT infrastructure, you can be assured of high demand for professionals with the Oracle Certified Associate and Oracle Certified Professional certifications Sybex is proud to have helped thousands of Oracle certification candidates prepare for the exams over the years, and we are excited about the opportunity to continue to provide professionals like you with the skills needed to succeed in the highly competitive IT industry Our authors and editors have worked hard to ensure that the Oracle9i Study Guide you hold in your hands is comprehensive, in-depth, and pedagogically sound We’re confident that this book will meet and exceed the demanding standards of the certification marketplace and help you, the Oracle9i certification candidate, succeed in your endeavors Good luck in pursuit of your Oracle9i certification! Neil Edde Associate Publisher—Certification Sybex, Inc Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Software License Agreement: Terms and Conditions The media and/or any online materials accompanying this book that are available now or in the future contain programs and/or text files (the “Software”) to be used in connection with the book SYBEX hereby grants to you a license to use the Software, subject to the terms that follow Your purchase, acceptance, or use of the Software will constitute your acceptance of such terms The Software compilation is the property of SYBEX unless otherwise indicated and is protected by copyright to SYBEX or other copyright owner(s) as indicated in the media files (the “Owner(s)”) You are hereby granted a single-user license to use the Software for your personal, noncommercial use only You may not reproduce, sell, distribute, publish, circulate, or commercially exploit the Software, or any portion thereof, without the written consent of SYBEX and the specific copyright owner(s) of any component software included on this media In the event that the Software or components include specific license requirements or end-user agreements, statements of condition, disclaimers, limitations, or warranties (“End-User License”), those End-User Licenses supersede the terms and conditions herein as to that particular Software component Your purchase, acceptance, or use of the Software will constitute your acceptance of such End-User Licenses Warranty SYBEX warrants the enclosed media to be free of physical defects for a period of ninety (90) days after purchase The Software is not available from SYBEX in any other form or media than that enclosed herein or posted to www.sybex.com If you discover a defect in the media during this warranty period, you may obtain a replacement of identical format at no charge by sending the defective media, postage prepaid, with proof of purchase to: SYBEX Inc Product Support Department 1151 Marina Village Parkway Alameda, CA 94501 Web: http://www.sybex.com After the 90-day period, you can obtain replacement media of identical format by sending us the defective disk, proof of purchase, and a check or money order for $10, payable to SYBEX Disclaimer Reusable Code in This Book SYBEX makes no warranty or representation, either expressed or implied, with respect to the Software or its contents, quality, performance, merchantability, or fitness for a particular purpose In no event will SYBEX, its distributors, or dealers be liable to you or any other party for direct, indirect, special, incidental, consequential, or other damages arising out of the use of or inability to use the Software or its contents even if advised of the possibility of such damage In the event that the Software includes an online update feature, SYBEX further disclaims any obligation to provide this feature for any specific duration other than the initial posting The authors created reusable code in this publication expressly for reuse for readers Sybex grants readers permission to reuse for any purpose the code found in this publication or its accompanying CD-ROM so long as all of the authors are attributed in any application containing the reusable code, and the code itself is never sold or commercially exploited as a stand-alone product The exclusion of implied warranties is not permitted by some states Therefore, the above exclusion may not apply to you This warranty provides you with specific legal rights; there may be other rights that you may have that vary from state to state The pricing of the book with the Software by SYBEX reflects the allocation of risk and limitations on liability contained in this agreement of Terms and Conditions Software Support Shareware Distribution Components of the supplemental Software and any offers associated with them may be supported by the specific Owner(s) of that material, but they are not supported by SYBEX Information regarding any available support may be obtained from the Owner(s) using the information provided in the appropriate read.me files or listed elsewhere on the media This Software may contain various programs that are distributed as shareware Copyright laws apply to both shareware and ordinary commercial software, and the copyright Owner(s) retains all rights If you try a shareware program and continue using it, you are expected to register it Individual programs differ on details of trial periods, registration, and payment Please observe the requirements stated in appropriate files By purchase, use or acceptance of the Software you further agree to comply with all export laws and regulations of the United States as such laws and regulations may exist from time to time Should the manufacturer(s) or other Owner(s) cease to offer support or decline to honor any offer, SYBEX bears no responsibility This notice concerning support for the Software is provided for your information only SYBEX is not the agent or principal of the Owner(s), and SYBEX is in no way responsible for providing any support for the Software, nor is it liable or responsible for any support provided, or not provided, by the Owner(s) Copy Protection The Software in whole or in part may or may not be copyprotected or encrypted However, in all cases, reselling or redistributing these files without authorization is expressly forbidden except as specifically provided for by the Owner(s) therein Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com To Brenda and Emily, the two most important people in my life —Joseph C Johnson Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Acknowledgments I would like to acknowledge the many people who helped shape the professional experiences that led to my writing of this book This includes my Oracle colleagues at Greenbrier & Russel, Inc., whose Oracle challenges have also helped shape my own: Christopher Guillaume, John Golden, Jesus Quinones, Jim Whittle, and Jane Yang Included too are the clients and fellow DBAs who have offered me many interesting Oracle experiences in recent years, including: Jonathan Jackson, Tim Eleyet, Linda Ramme, Bob Budden, Greg Van Haren and John Aaholm at American Transmission Company; Tony Gastel and Audrey Smith at Highland Community College; George Carpenter and Lorin Weiler at Dean Health Plan; Mike Gavin, Jerri Wang, Dan Hartsman, Thomas Baas, and Ted Drankus at Milwaukee Area Technical College; and Jim Schwarz and Reginald Bron at Snap-On Tools I’d like to thank Matt Weishan for writing or revising all of the questions in the 9i book and on the CD I’m glad we were able to work together again on this project Thanks also to Bob Bryla and Ashok Hanumanth for their efforts during the technical reviews, and all the people at Sybex who made this project a smooth one: Christine McGeever, Jeff Kellum, Dan Schiff, Linda Stephenson, and Leslie Light Finally, I say thank you to my wife, Brenda, who somehow always found the time to help me by proofreading chapters or fixing up screen shots whenever deadlines were looming Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Introduction There is high demand for professionals in the information technology (IT) industry, and Oracle certifications are the hottest credential in the database world You have made the right decision to pursue certification, because being Oracle certified will give you a distinct advantage in this highly competitive market Many readers may already be familiar with Oracle and not need an introduction to the Oracle database world For those who aren’t familiar with the company, Oracle, founded in 1977, sold the first commercial relational database and is now the world’s leading database company and second-largest independent software company, with revenues of more than $10 billion, serving more than 145 countries Oracle databases are the de facto standard for large Internet sites, and Oracle advertisers are boastful but honest when they proclaim, “The Internet Runs on Oracle.” Almost all big Internet sites run Oracle databases Oracle’s penetration of the database market runs deep and is not limited to dot-com implementations Enterprise resource planning (ERP) application suites, data warehouses, and custom applications at many companies rely on Oracle The demand for DBA resources remains higher than others during weak economic times This book is intended to help you on your exciting path toward becoming an Oracle Certified Professional (OCP) and Oracle Certified Master (OCM) Basic knowledge of Oracle SQL is an advantage when reading this book but is not mandatory Using this book and a practice database, you can start learning Oracle and pass the 1Z0-033 test: Oracle9i Database: Performance Tuning Why Become an Oracle Certified Professional? The number one reason to become an OCP is to gain more visibility and greater access to the industry’s most challenging opportunities Oracle certification is the best way to demonstrate your knowledge and skills in Oracle database systems The certification tests are scenario-based, which is the most effective way to assess your hands-on expertise and critical problemsolving skills Certification is proof of your knowledge and shows that you have the skills required to support Oracle core products The Oracle certification Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com xviii Introduction program can help a company identify proven performers who have demonstrated their skills and who can support the company’s investment in Oracle technology It demonstrates that you have a solid understanding of your job role and the Oracle products used in that role OCPs are among the best paid in the IT industry Salary surveys consistently show the OCP certification to yield higher salaries than other certifications, including Microsoft, Novell, and Cisco So, whether you are beginning a career, changing careers, securing your present position, or seeking to refine and promote your position, this book is for you! Oracle Certifications Oracle certifications follow a track that is oriented toward a job role There are database administration, database operator, and developer tracks Within each track, Oracle has a three-tiered certification program: The first tier is the Oracle Certified Associate (OCA) OCA certification typically requires you to complete two exams, the first via the Internet and the second in a proctored environment The next tier is the Oracle Certified Professional (OCP), which builds upon and requires an OCA certification The additional requirements for OCP certification are additional proctored exams The third and highest tier is the Oracle Certified Master (OCM) OCM certification builds upon and requires OCP certification To achieve OCM certification, you must attend two advanced Oracle Education classroom courses (from a specific list of qualifying courses) and complete a practicum exam The following material will address only the database administration track, because at the time of this writing, it was the only 9i track offered by Oracle The other tracks have and 8i certifications and will undoubtedly have 9i certifications See the Oracle website at http://www.oracle com/education/certification/ for the latest information Oracle9i Certified Database Associate The role of the database administrator (DBA) has become a key to success in today’s highly complex database systems The best DBAs work behind the scenes, but are in the spotlight when critical issues arise They plan, create, maintain, and ensure that the database is available for the business They Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Introduction xix are always watching the database for performance issues and to prevent unscheduled downtime The DBA’s job requires broad understanding of the architecture of an Oracle database and expertise in solving problems The Oracle9i Certified Database Associate is the entry-level certification for the database administration track and is required to advance toward the more senior certification tiers This certification requires you to pass two exams that demonstrate your knowledge of Oracle basics: 1Z0-007: Introduction to Oracle9i: SQL 1Z0-031: Oracle9i Database: Fundamentals I The 1Z0-007 exam, Introduction to Oracle9i: SQL, is offered on the Internet The 1Z0-031 exam, Oracle9i Database: Fundamentals I, is offered at a Sylvan Prometric facility Oracle9i Certified Database Administrator (OCP) The OCP tier of the database administration track challenges you to demonstrate your continuing experience and knowledge of Oracle technologies The Oracle9i Certified Database Administrator certification requires achievement of the Certified Database Associate tier, as well as passing the following two exams at a Sylvan Prometric facility: 1Z0-032: Oracle9i Database: Fundamentals II 1Z0-033: Oracle9i Database: Performance Tuning Oracle9i Certified Master The Oracle9i Certified Master is the highest level of certification that Oracle offers To become a certified master, you must first achieve OCP status, then complete two advanced instructor-led classes at an Oracle education facility, and finally pass a hands-on exam at Oracle Education The classes and practicum exam are offered only at an Oracle education facility and may require travel The advanced classes that will count toward your OCM requirement include the following: Oracle9i: Program with PL/SQL Oracle9i: Advanced PL/SQL Oracle9i: SQL Tuning Workshop Oracle9i: High Availability in an Internet Environment Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 559 B B-Tree Index index types The balanced tree index structure used by several Oracle BACKGROUND_DUMP_DEST The init.ora parameter that specifies the directory where trace files generated by the Oracle background processes should be created Bind Variables Containers that hold passed-in values in SQL statements so that the actual values themselves are not included in the statement Use of bind variables increases the Shared Pool hit ratio Bitmap The binary string used to indicate what the contents of a column are in a Bitmapped index A value of indicates that the specified value exists in the column; a value of indicates that it does not Bitmap Index The binary mapping of the contents of an indexed column Used when Bitmap indexes are created on table columns Blocks The smallest unit of I/O in the Oracle database is one Oracle block Each block stores data associated with a particular segment type (e.g., table or index) Buffer Cache Advisor Allows the DBA to estimate the potential improvement in Buffer Cache hit ratios if changes were made to the size of the Database Buffer cache Buffer Pool Used to cache segment buffers in the Database Buffer Cache based on the nature of the segment’s usage Frequently accessed segments can be cached in the Keep Pool and infrequently accessed segments can be cached in the Recycle Pool All other segments will be cached in the Default Pool Busy Ratio The busy ratio is used to determine how frequently application users are requesting Shared Server components High busy ratios indicate that additional Shared Server resources (e.g., Dispatchers and Shared Servers) may need to be added Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 560 Glossary C Cache Hit The act of finding an object you need in memory and therefore not having to read it from disk (in the case of the Database Buffer Cache) or parse it (in the case of the Shared Pool) Cache Miss The act of not finding an object you need in memory and therefore having to read it from disk (in the case of the Database Buffer Cache) or parse it (in the case of the Shared Pool) Cache Table A table whose buffers are placed at the most recently used end of the LRU List even when accessed via a full table scan Cardinality A measure of the variation in the data stored within a table’s column If a column contains many distinct values, it is said to have high cardinality If a column contains few distinct values, it is said to have low cardinality Checkpoint Process (CKPT) The Oracle background process that updates the control file and datafile headers at a database checkpoint event Cluster A physical storage method that allows the data from one or more tables to be stored in the same physical blocks and clustered around a common value (the cluster key) Composite Partitioning A table partitioning technique that uses a combination of range and hash partitioning to store table data Compressed An index type that minimizes disk usage and disk I/Os by storing one value for each index key along with all the ROWIDs associated with that index Contention The tuning problem that occurs any time two or more processes compete for access to the same resource Control File The physical database files that store information about the database’s name, physical structure, and recovery timestamps Cost-Based Optimizer (CBO) The Oracle optimizer mode that examines all possible execution plans for a given SQL statement and then chooses the one with the lowest execution cost Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 561 D Data Concurrency The process of allowing as many users as possible to access segment data by using the least restrictive locks Data Consistency The process of always presenting an application user with data that is consistent within their session Data Dictionary Cache dictionary information The section of the Shared Pool that caches data Data Dictionary View segment information The DBA views that show static database, user, and Data Lock A lock that is taken out on segments when DML is being performed on those segments Database The physical files that comprise a database: Control Files, Datafiles, and Redo Logs Database Checkpoint The moment in time when the contents of the Database Buffer Cache and the Redo Log Buffer are written to disk and the database control file and datafile headers are updated to record the occurrence of the event Database Event A specific action that occurs at the database level Specific events can be monitored and managed by the Oracle Enterprise Manager Intelligent Agent Database Writer (DBW0) The Oracle background process that writes database buffers from the SGA to the Datafiles Datafile The physical database files that store the application’s tables and indexes Deadlock The special locking problem where two or more users are each waiting for the other to release a lock before their processing can proceed Decision Support Systems A system that is characterized by long, querybased access of large tables in order to gain insights into trends or patterns in the data Dedicated Server single session A server process that processes the requests of a Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 562 Glossary Default Pool The Database Buffer Cache buffer pool used to cache any segments that have not been designated for storage in the Keep or Recycle Pools Degree of Parallelism Specifies the number of process to start when executing a query using Oracle’s Parallel Query feature Dictionary Lock A lock that is taken out on segments when DDL commands are being performed on those segments Dirty List The list of buffers in the Database Buffer Cache whose contents not match the copy of the block on disk Dispatcher A dispatcher is an Oracle Server process that is responsible for processing the requests of many clients Used in a shared server environment Dynamic Performance View The V$ views which show statistical information collected from the time the instance was started until the present E Emphasis Method A method of assigning resources to consumer groups by specifying a value between and 100 percent for the resource CPU resources are assigned in this manner Enqueue The process Oracle uses to keep track of the type and sequence of locking requests issued by application users Execute The stage in SQL statement processing where the action specified in the statement is actually performed Explain Plan A step-by-step description of the operations an SQL operation will perform when it executes Extent A contiguous set of database blocks that belong to a particular segment Extent Map An entry in the header block of the initial extent of a segment that tells the segment where the rest of the segment’s extents are located and their sizes Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 563 F Fetch The stage in SQL statement processing when the rows selected by the statement are returned to the user Fixit Job A job that runs when a specific triggering event associated with that Fixit Job occurs in the database Free List The list of database blocks belonging to a particular segment that are available for inserts Free List Contention Excessive requests for access to a table’s Free List that result in waits for users performing insert activity Function-based Index Index that uses a function in its initial definition This index can be considered for use by the cost-based optimizer when queries using that same function on that same table column are issued G Get The act of finding a desired SQL statement or database block already cached in memory so that it does not need to be parsed or read from disk, respectively Granule A portion of contiguous memory allocated within the Database Buffer Cache in the SGA Graphical User Interface (GUI) Software that utilizes graphics instead of command-line syntax as a user interface H Hash Cluster A physical storage method that allows Oracle to find row values using a hashing algorithm instead of using a conventional B-Tree index Hash Partition A technique for partitioning the contents of a table wherein the hash key column is passed through a hashing algorithm in Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 564 Glossary order to determine into which partition a newly inserted row should be placed Hash Values The value that is returned from a hashing algorithm after a value is passed into that algorithm Heap Table A table whose rows are not stored in any particular order Instead, the row storage order is determined by the order in which available blocks came on and off the free list High Water Mark The block ID of the highest block number used to store data for a table All blocks up to the high water mark block are read during a full table scan Hints Keywords which, when embedded within comments in SQL statements, cause the Oracle optimizer to behave in a specified manner Histogram Statistics that are used to inform the Cost Based Optimizer of the actual distribution of data within a particular column Hit Ratio A calculation of how frequently users are finding their requested SQL and data buffers to already be cached in memory I Immediate Latch A latch type that immediately retries obtaining a previously busy latch without waiting Index Cluster A technique for storing the data from one or more tables in the same physical block Index Organized Table (IOT) A table whose data is physically stored in the same B-Tree structure found in indexes init.ora The physical file that contains the database and instance configuration parameters Instance The collection of memory structures associated with an Oracle database These structures include the System Global Area and all the Oracle background processes (e.g., PMON, SMON, etc.) Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 565 J Java Pool The portion of the Shared Pool that is set aside for caching session-specific Java code and application variables during Java program execution Java Virtual Machine Software that converts Java code into machine language for a particular operating system and then executes it K Keep Pool The Database Buffer Cache buffer pool used to cache frequently used segments Kernel The essential core components of a server’s operating system L Large Pool A portion of the SGA that is set aside for buffering the activities of I/O intensive operations like Recovery Manager and I/O Slaves as well as Shared Server information Latch A mechanism used to protect access to Oracle’s shared memory structures Least Recently Used (LRU) The type of algorithm used by the Oracle Server to determine which objects should be moved out of the SGA in order to make room for new objects Library Cache The section of the Shared Pool that caches SQL statements, PL/SQL blocks, triggers and sequences List Partitions A partitioning technique that stores table data in partitions based on the character value in the partition key column Locally Managed Tablespace A tablespace whose space allocation and management is handled by an extent map in the header of the tablespace’s datafile instead of by entries in the data dictionary Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 566 Glossary Lock Contention Excessive waits caused by locks that are too restrictive or are held too long Log Writer (LGWR) The Oracle background process responsible for emptying the contents of the Redo Log Buffer to the online redo log LRU List The mechanism used by Oracle to maintain the contents of the Shared Pool and Database Buffer Cache Items in these memory structures that are not used frequently will be overwritten by new items M Mapping Table Used by bitmapped indexes to map physical to logical row IDs when bitmap indexes are built on index-organized tables Materialized View A view that physically stores the summary results of a query against the view’s base tables MAX_DUMP_FILE_SIZE The init.ora parameter that specifies the maximum size that a user trace file can grow to O Online Redo Log The active Redo Log group that is currently being written to by Log Writer (LGWR) Online Transaction Processing A system that is characterized by short DML transactions that emphasize response time Optimal Flexible Architecture The naming convention for devices and directories that are home to Oracle-related products and files Oracle Diagnostics Pack A collection of GUI tools for performing database monitoring, tuning and troubleshooting Oracle Enterprise Manager (OEM) The set of tools that enable DBAs to manage and monitor Oracle databases in a GUI environment Oracle Enterprise Manager Repository The collection of tables that store the Oracle Expert rule base, tuning preferences, and gathered statistics Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 567 Oracle Expert The component of the Oracle Enterprise Manager Oracle Performance Pack used to gather and analyze performance statistics in order to make tuning recommendations according to a stored rule base Oracle Intelligent Agent The autonomous OS process that runs on each server node being managed by the Oracle Enterprise Manager Console The Intelligent Agent monitors the databases on its node and performs event notification and job scheduling actions on behalf of the OEM console Oracle Performance Manager The Oracle Enterprise Manager GUI tool that allows you to graphically monitor the performance of a selected database Oracle Server All the logical and physical components that make up an Oracle system, including the System Global Area, background processes, user processes, Datafiles, Redo Logs, Control Files, and configuration files Oracle SQL Analyze A component of the Enterprise Manager Tuning Pack, this GUI tools analyzes SQL statements and recommends changes that may improve their performance Oracle TopSessions The Oracle Enterprise Manager GUI tool for identifying and monitoring the user and background processes that are interacting with the instance Oracle Trace Data Viewer A component of Enterprise Manager Diagnostics Pack used to view the contents of user trace files P P-Code A compiled version of a SQL statement that is cached in the Shared Pool Parse The stage in SQL statement processing where the statement is checked for syntactic correctness, security, and object resolution Parse Lock The lock type taken out on an object at parse time Partition A subset row in a table that stores related data based on the values in a specified partition key column Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 568 Glossary Partition Pruning The process the Cost Based Optimizer uses to eliminate from consideration table partitions that are not relevant to a particular query Password File The physical file used by Oracle to authenticate database users who are connecting with SYSDBA or SYSOPER privileges Pending Area The location where resource consumer groups, resource plans, and resource plan directives are temporarily stored until they are committed to the database Physical Memory The amount of memory that is defined by the physical memory chips installed in the server Pinning The process of locking a PL/SQL package into the Shared Pool so that it is never aged out by the Shared Pool’s LRU mechanism Plan Equivalence The determining factor of whether a stored outline will be used to execute a particular query If the plans are equivalent, the stored outline will be used Primary Block Size The block size that was specified at database creation This value is established by the setting for DB_BLOCK_SIZE parameter in the init.ora Private Outline altered it A stored outline that is visible only to the session that Process An entity that runs independently on the operating system and consumes its own OS resources (such as CPU and memory) Process Global Area The memory space used to support the activities of each user’s Server Process Process Monitor (PMON) The Oracle background process responsible for cleaning up failed user connections R RAID A hardware solution designed to minimize downtime by striping data across several devices A failure by any one device will not interrupt Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 569 processing since the remaining devices can reconstruct the data from the missing device Range Partitioning A technique for partitioning the contents of a table wherein the value in the partition key column is compared to the nonoverlapping ranges of values that the make up the table’s partitions in order to determine into which partition a newly inserted row should be placed Recycle Pool The Database Buffer Cache buffer pool used to cache infrequently used segments Redo Log The physical database files that store transaction recovery information Redo Log Buffer The portion of the SGA that stores information needed to recover user transactions REPORT.TXT The text file created by executing the ULTBSTAT.SQL and UTLESTAT.SQL scripts The REPORT.TXT file contains extensive performance-tuning related statistics for the period between the execution of ULTBSTAT.SQL and ULTESTAT.SQL Request Queue The location in the SGA where the dispatcher places a client request to be executed by a shared server Resource Consumer Group database resources A group of users who have similar needs for Resource Plan A collection of resource plan directives that are used to implement resource management Resource Plan Directive Specifies the CPU, degree-of-parallelism, undo, session, and execution duration resources allocated to a particular resource plan Response Queue The location in the SGA where shared servers place completed client requests Each dispatcher has its own response queue Response Time The amount of time it takes to perform a specific operation on a system Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 570 Glossary Reverse Key Index (RKI) A B-Tree index type that reverses the contents of the indexed column before creating the index Rollback The process of undoing a transaction and restoring modified data back to its original state Row Chaining Occurs whenever a table’s rows are too large to fit within a single Oracle block and therefore span two or more blocks Row Migration A row of table data that originally fit into a single database block, but which was moved to a new block with more free space when the row was updated Rule-Based Optimizer The Oracle optimizer mode that uses a set of predefined rules when determining the best execution plan for a given SQL statement S Scalability The ability of a system to continue to perform adequately as additional demands are placed upon it Segment Header The block or blocks that store storage information about a segment (i.e., table, index, or rollback segment) Service Level Agreement A written document that outlines the expectations of the user community with regard to a system’s availability and performance Shared Pool The portion of the SGA that caches SQL statements issued against the instance Shared Pool Reserved Area Portion of the Shared Pool that can be set aside specifically for use by large PL/SQL packages and triggers Shared Server The Oracle processes responsible for executing a client request in a multithreaded server environment Sort Sorting occurs whenever data need to be placed in a specific order One example of sorting is the use of an ORDER BY clause in an SQL statement Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 571 STATSPACK The Oracle-supplied utility for capturing and analyzing database and instance performance statistics over several user-defined time spans Stripe Depth The amount of data that will be written to one device in a RAID set before moving to the next device in that set Stripe Width created The number of physical devices across which a RAID set is Striping The process of causing a datafile to span multiple physical devices in order to improve I/O Stored Outlines The predetermined, stored execution plan for a given SQL statement that is used each time that statement is issued Synchronous A method of performing disk I/O that does require the services of an OS layer These are usually referred to as file systems or “cooked” devices System Global Area (SGA) Oracle’s shared memory structure used to cache SQL statements, data buffers, and transaction recovery information System Monitor The Oracle background process responsible for performing instance recovery, managing sort segments, and coalescing of free space in tablespaces System-managed Undo See Automatic Undo Management T Tablespace The logical division of storage within a database Multiple tablespaces are usually created to store each type of application segment (e.g., tables, indexes, rollback segments) Each tablespace is composed of one or more Datafiles Tempfile A special type of datafile used in the creation of temporary tablespaces Thread An independent sequence of instructions that executes within a single operating system process Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com 572 Glossary Throughput of time The amount of work performed by a system in a given period TKPROF The Oracle command-line utility for formatting user trace files so that the resulting file can be examined for tuning information Trace The process of creating a text file that contains details about the operations performed by a user or background process Trace File A text file that contains information about all the actions performed by a user or background process during the time that tracing was active U Undo Segments Undo segments (also known as rollback segments) are used to store the before-image of a user’s changed data These before-images are used for both read consistency and transaction recovery User Global Area The section of the Shared Pool that caches shared user information when using the Multithreaded Server mode User Server Process The OS process that each connected database user has on the server when the instance is operated in Dedicated Server mode The User Server process communicates with the System Global Area on behalf of the user USER_DUMP_DEST The init.ora parameter that specifies the directory where trace files generated by the Oracle Server processes should be created UTLBSTAT.SQL The Oracle-supplied script that is run at the beginning of the tuning period to be examined UTLESTAT.SQL The Oracle-supplied script that is run at the end of the tuning period to be examined The script also generates the output file REPORT.TXT Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com Glossary 573 V Virtual Memory Disk space that is used by the operating system to temporarily cache in-memory processes or memory pages whenever demands on the server’s physical memory exceed its physical size W Willing-to-Wait Latch A latch type that waits before trying to obtain a previously busy latch again Write List The mechanism for managing dirty buffers in the Database Buffer Cache Keeps track of all the blocks that have been modified by application users through the use of INSERT, DELETE, or UPDATE statements, but have not yet been written to disk Copyright ©2002 SYBEX, Inc., Alameda, CA www.sybex.com ... OCP level Sybex offers several study guides to help you achieve this certification: OCA /OCP: Introduction to Oracle9i SQL Study Guide (exam 1Z0-007: Introduction to Oracle9i: SQL) OCA /OCP: Oracle9i ... Fundamentals I Study Guide (exam 1Z0-031: Oracle9i Database: Fundamentals I) OCP: Oracle9i DBA Fundamentals II Study Guide (exam 1Z0-032: Oracle9i Database: Fundamentals II) OCP: Oracle9i DBA Performance. .. than prepared for the exam Copyright 2002 SYBEX, Inc., Alameda, CA www .sybex. com xxvi Introduction OCP: Oracle9i Performance Tuning Study Guide in PDF Sybex is now offering this Oracle certification