Oracle9i DBA Fundamentals I

Transcription

1 Oracle9i DBA Fundamentals I

2 ii Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

3 Oracle9i DBA Fundamentals I George Trujillo Published by ITCourseware, LLC, 7245 South Havana St., Suite 100, Centennial, CO Editor: Rick Sussenbach Assistant Editor: Jan Waleri Copyright 2004 by Technology Framers, LLC. Portions Copyright ITCourseware, LLC. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage retrieval system, without permission in writing from the publisher. Inquiries should be addressed to ITCourseware, LLC, 7245 South Havana St., Suite 100, Centennial, CO 80112, (303) All brand names, product names, trademarks, and registered trademarks are the property of their respective owners. Version Technology Framers, LLC. iii All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

4 iv Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

5 Course Description Overview This class will develop the key fundamental skills necessary to be an Oracle DBA. Students will design and create a server using the Optimal Flexible Architecture (OFA), configure logical and physical structures, set up database and user security, add and administer users, and monitor and tune main server areas. New Oracle9i features such as Oracle Managed Files, Automatic segment management, undo tablespaces, default temporary tablespaces, dynamic memory configuration and server parameter files will be covered.. Best practices and techniques are emphasized throughout the class. Each student will create a toolkit of administration scripts for database management and tuning by the end of this class. This class will also address issues for DBAs having to support Oracle8i and Oracle9i databases.. Prerequisites Students must have completed the five-day Oracle8i or Oracle9i introduction course or at least six months working in an Oracle technical environment. Students must walk into the class with a understanding of relational database concepts, SQL and PL/SQL programming skills and a solid understanding of Oracle schema objects (tables, views, sequences, synonyms, procedures, functions and packages). Objectives Upon completion of this course, students will understand: The Oracle9i Server architecture and how it works The benefits of the Optimal Flexible Architecture Debugging the server and solving problems using the Oracle Data Dictionary Dynamic memory configuration Automatic segment space management Management of logical and physical storage structures (tablespaces, data files and schema objects) The main features of Oracle server and user security Different types of server configurations (JServer, Shared Server, RAC, replication, etc.) Oracle utilities (export, import, SQL*Plus and SQL*Loader) Function-based indexes, index-organized tables, and reverse indexes Rule-based optimization and new features of the cost-based optimizer Oracle managed files Main areas of an Oracle9i server to monitor and performance tune Duration Five days Technology Framers, LLC. v All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

6 vi Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

7 Understanding the Oracle9i Server Architecture 1-1 Chapter Overview Responsibilities of a DBA Changing DBA Environments What is an Oracle Server? Oracle Versioning Server Architectural Overview Operating System Environment Operating System Environment Important Subdirectories in ORACLE_HOME Oracle Product Subdirectories Oracle Instance Components Database Files Control Files Redo Log Files Redo Log Files (continued) Logical Storage Structures Oracle Block Sizes Blocks, Extents, and Segments Different Types of Segments Tablespaces Logical Structural Design System Change Numbers Different Versions of Oracle Oracle8.0 The Object-Relational Release Oracle Ceilings Additional Database Limits Oracle8i The Internet Release Oracle9i Release 1 The ebusiness Database Oracle9i Release 2 The Object-Relational OLAP Database Oracle Products and Architectures DBA Management Pack Understanding your Oracle Server Layout Review Questions Review Question Answers Summary Exercises Technology Framers, LLC. vii All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

8 Oracle Memory Structures and Processes 2-1 Chapter Overview Oracle Instance Review Database Buffer Cache Database Buffer Cache The LRU and Dirty Lists Server Processes and the Buffer Cache DBWR and the Buffer Cache MTTR and Checkpoint intervals Checkpoints Determining When Checkpoints Occur Methods for Controlling Check pointing Methods for Controlling Check pointing (2) V$INSTANCE_RECOVERY View Calculating Checkpointing MTTR Advisor Minimal I/O Recovery Defining Multiple DB Cache Buffer Pools Defining the Database Buffer Pools (Oracle8i style) Database Buffer Pool Parameters (Oracle8i style) The Buffer Pool Parameter Defining Storage for Buffer Pools Calculating the Hit Ratio for Buffer Pools Calculating Buffer Pool Sizes Latch Contention Caching Tables Calculating Cache Usage of Schema Objects Redo Log Buffer Cache Shared Pool Area Large Pool Area Large Pool Parameters Java Pool Size The Oracle JVM Impacting Server Process Memory Background Processes Required Background Processes Additional Background Processes Listing Processes Review Questions Summary Exercises viii Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

9 Server Processes and Executing SQL 3-1 Chapter Overview Server Processes Program Global Areas User Global Area Dedicated Server Architecture Shared Server Architecture The Shared Server Architecture Deprecated Parameters Shared Server Parameters The Parse Phase Execution Plan Phase Execution and Fetch Phase Processing DML Statements Rule-based and Cost-based Optimizers Tuning Parallel Query Tuning Parallel Query Parallel DML Parallel DML Restrictions Summary Exercises Using the Data Dictionary 4-1 Chapter Overview What is the Oracle Data Dictionary? Base Tables and Static Views in the Data Dictionary Dynamic Views in the Data Dictionary ALL_% Static Views DBA_% Static Views USER_% Static Views USER_% Static Views Additional Views V$ Dynamic Views GV$ Dynamic Views GV$ Dynamic Views Useful Database Data Dictionary Views Looking at Data Dictionary Views Review Questions Review Question Answers Summary Exercises Technology Framers, LLC. ix All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

10 Starting and Shutting Down an Oracle Server 5-1 Chapter Overview Database Utilities The Server Manager Tool (Obsolete in Oracle9i) SQL*Plus Features SQL*Plus Commands Additional Commands The Parameter File Oracle Universal Installer Oracle Universal Installer The Database Configuration Assistant Setting up a Parameter File Important Parameters for Database Creation Starting an Oracle Server The STARTUP command Startup and Shutdown Privileges Shutdown Steps SHUTDOWN Command Options ALTER DATABASE Command ALTER DATABASE Examples Alert and Trace Files Working with Data Dictionary Views Dynamic versus Static Parameters Which Parameters are Dynamic versus Static Parameters Dynamic versus Static Parameters Review Questions Review Question Answers Summary Exercises Server Parameter File 6-1 Chapter Overview Definition of the Server Parameter File (SPFILE) Definition of the Server Parameter File (SPFILE) Operation of the SPFILE Operation of the SPFILE (2) Steps for Creating an SPFILE Creating an SPFILE Changing Parameters in the SPFILE Changing Parameters in the SPFILE (2) Changing Parameters in the SPFILE - Examples Backing up the SPFILE Gathering Information About Parameters SPFILE FAQs Summary x Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

11 Summary(2) Review Questions Exercises Dynamic Memory Management 7-1 Chapter Overview Setting up SQL Work Areas Setting up SQL Work Areas Defining Automatic PGA Memory Management SQL Work Areas versus the PGA Aggregate Target Setting the PGA Target Memory Size Displaying Workarea Information Using a PGA Workarea Dynamic SGA Granules Granules (continued) Changing the Database Buffer Cache Changing the Database Buffer Cache V$BUFFER_POOL Changing the Shared Pool Size Database Buffer Cache Parameters Multiple Database Buffer Caches Deprecated Parameters Advisory Parameter V$DB_CACHE_ADVICE Summary Exercises Managing Tablespaces and Data Files 8-1 Chapter Overview Review Logical and Physical Structure Relationships Tablespaces Different Types of Tablespaces The SYSTEM Tablespace CREATE TABLESPACE Command CREATE TABLESPACE Clauses Locally-Managed Tablespaces Locally Managed Tablespace Options Advantages of Locally Managed Tablespaces ALTER TABLESPACE syntax: Temporary Tablespaces CREATE TEMPORARY TABLESPACE Command Temporary Segments Tablespaces and Temporary Segments Technology Framers, LLC. xi All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

12 Database Default Temporary Tablespace Creating a Default Temporary Tablespace More on Temporary Tablespaces Read-only Tablespaces Viewing Active Transactions Coalescing Dictionary Managed Tablespaces Using the ALTER TABLESPACE command Taking Tablespaces ONLINE and OFFLINE Tablespace Offline Options Renaming a Data File Adding More Space to a Database Autoextending a Data File DROP TABLESPACE Command DROP TABLESPACE Command (continued) Dictionary-Managed Tablespaces Creating Dictionary-Managed Tablespaces Dictionary-Managed Temporary Tablespaces Dictionary versus Locally Managed Tablespaces Converting Dictionary and Local Tablespaces Migrating the Tablespace Management Type Data Dictionary Views Review Questions Summary Exercises Managing Rollback Segments 9-1 Chapter Overview Managing Before-Image Data Rollback Segments Private versus Public Rollback Segments Typical Layout for Rollback Segments Second Rollback Segment in SYSTEM Space Usage Sizing Rollback Segments The OPTIMAL Parameter CREATE ROLLBACK SEGMENT Command ALTER/DROP ROLLBACK SEGMENT Commands Using the SET TRANSACTION Command Data Dictionary Views for Rollback Segments More on Rollback Segments Recommendations for Rollback Segments Data Dictionary Views for Rollback Segments Review Questions Summary Exercise xii Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

13 Tablespace Management 10-1 Chapter Overview Automatic Undo Management Automatic Undo Management Creating an Undo Tablespace Automatic Mode for Managing Undo Space Automatic Undo Initialization Parameters The UNDO_RETENTION Parameter Creating an Undo Tablespace Defining an Undo Tablespace When Creating a Database Determining the Size of the Undo Tablespace Data File Determining the Size of the Undo Tablespace Data File (2) Dropping an Undo Tablespace Switching Undo Tablespaces Data Dictionary Views for Undo Information Undo versus Rollback Segments Multiple Block Size Support Multiple Block Size Support (2) Setting up Multiple Block Sizes Setting up Multiple Block Sizes (2) Information About Block Sizes Summary Review Questions Exercises Segment Management 11-1 Chapter Overview High Throughput Systems High Throughput Systems Automatic Segment-Space Management Creating Tablespaces Using Automatic Segment-Space Management Space Management Creating Objects in Automatic Segment-Space Managed Tablespaces Creating Objects in Automatic Segment-Space Managed Tablespaces (2) Space Deallocation With Automatic Segment-Space Management The DBMS_SPACE Package The SPACE_USAGE Parameters Example using SPACE_USAGE Space Deallocation Statements Viewing Space Usage Information Summary Review Questions Exercises Technology Framers, LLC. xiii All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

14 Managing Tables 12-1 Chapter Overview Creating Tables Creating Table Syntax Create the SALE_TAB Table ROWIDs Creating Segments in Tablespaces Column Datatypes Column Datatypes Column Datatypes Different Types of Tables Global Temporary Tables Clustered Tables Database Block Block Utilization Parameters Row Migration and Chaining Storage Clause Options Storage Clause Parameters Storage Clause Examples Managing Extent Growth Moving Tables Removing Data From Tables Renaming Tables Modifying Column Definitions Defining Columns to be Unused Dropping Columns Segment High Water Mark and Segment Header Calculate the HWM of a Segment More ALTER TABLE Examples Online Table Redefinitions DBMS_REDEFINITION Package Redefining a Table Validate Structure Online The TRUNCATE Command Data Dictionary Views for Tables Listing of Columns for Main Views Review Questions Summary Exercises xiv Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

15 Managing Indexes 13-1 Chapter Overview Index Types B*-tree Indexes Creating B*-Tree Indexes Index Attributes Maintaining Indexes Maintaining Indexes (continued) Keep B*Tree Indexes Balanced Keep B*Tree Indexes Balanced Composite Indexes Creating a Composite Index Skip Scans Reverse Key Indexes Reverse Key Indexes (continued) Bitmap Indexes Bitmap Indexes Cluster (B*Tree) Indexes Cluster (B*Tree) Indexes (continued) Index Organized Tables Index Organized Tables (continued) Function-Based Indexes Function-based Indexes (continued) Domain Indexes Domain Index Overview Index Options Index Options (continued) Index Maintenance Analyzing the Index Rebuilding the Index Rebuilding the Index (2) Online Index Rebuilds Index Organized Table High Availability Features Examples of IOT Online Operations Coalescing the Index Bitmap Join Indexes Multiple Bitmap Join Indexes How They Work Bitmap Join Indexes An Example Bitmap Join Indexes Restrictions Indexes on Primary Keys Export and Import of Indexes SQL*Loader and Indexes Review Questions Summary Exercises Technology Framers, LLC. xv All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

16 Managing Constraints 14-1 Chapter Overview Data Integrity Different Types of Constraints Inline Constraints Out-of-Line Constraints Constraint Names Primary Key Constraints Foreign Key Constraints Foreign Key Constraints (Examples) Foreign Key Constraints (continued) Unique Constraints Not Null Constraints Check Constraints Viewing Constraint Information Constraints can be Deferred Enabling and Disabling Constraints Creating a Deferred Constraint Setting Deferred Constraints Setting the RELY Flag Additional Constraint Features Explicit Index Definition More on the USING INDEX Statement USING INDEX Syntax USING INDEX Example Dropping or Disabling Constraints and Indexes Reducing Locking on Foreign Key Tables Caching Primary Key Values Review Questions Summary Exercises Administration of Control Files 15-1 Chapter Overview Control File Contents Working with Control Files Multiplexing Control Files The CREATE CONTROLFILE Command Log Sequence Numbers Reviewing Checkpoints Reviewing Checkpoint Events Instance Recovery Managing Checkpointing Multiple DBWR IO Processes DB_BLOCK_CHECKING xvi Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

17 DB_BLOCK_CHECKSUM FAST_START_PARALLEL_ROLLBACK Summary Exercises Administration of Redo Log Files 16-1 Chapter Overview Review of Redo Log Files Writing to Redo Log Files Adding and Clearing Online Redo Log Files Dropping Online Redo Log Files Renaming Online Redo Log Files Archivelog Mode Setting up Archiving Mandatory or Optional Destinations Managing Archive Destinations Changing the ArchiveLog Mode Dynamic Archive Parameters ARCHIVE LOG LIST Command Data Dictionary Views for Redo Log Files Review Questions Summary Exercises Oracle Managed Files 17-1 Chapter Overview Why Use Oracle Managed Files? Why Use Oracle Managed Files? The Mechanism of OMF OMF Data Files OMF Naming Conventions O9iR2 OMF Naming Conventions DB_CREATE_FILE_DEST DB_CREATE_ONLINE_LOG_DEST_n Using OMF in Database Creation Using OMF in Database Creation (2) Using OMF in Database Creation (3) OMF and Online Redo Log Files OMF and Online Redo Log Files (2) OMF, Data Files, and Tablespaces OMF, Data Files, and Tablespaces (2) Renaming OMF Data Files More on Renaming OMF Data Files OMF and Control Files Technology Framers, LLC. xvii All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

18 OMF and Control Files (2) OMF and Control Files (3) OMF and Control Files (4) Summary Review Questions Review Questions (2) Exercises Managing Users and Profiles 18-1 Chapter Overview Creating Users CREATE USER Command Assigning Quotas to Users CREATE USER Examples ALTER USER Command ALTER USER Examples Protecting the System Tablespace Creating Profiles CREATE PROFILE Example Database Resource Limits Security Guidelines Review Questions Summary Exercises Security Administration 19-1 Chapter Overview System Privileges System Privileges Roles Granting Privileges Viewing System Privileges Granting Object Privileges Privileges and the User Group PUBLIC Revoking System Privileges and Roles Object Privileges Database Authentication Predefined Roles Setting up a Role Parent versus Child Roles Working with Default Roles Secure Application Role Secure Application Role Example Enabling and Disabling Roles xviii Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

19 Guidelines and Standards for Roles Additional Security Features Review Questions Summary Exercises Additional Security Features 20-1 Chapter Overview Enhanced Security Password Management Password Management Features Password Management Features Password Resource Limits Password Complexity Setting up Password Management Defining a Profile with Password Limits Defining a Profile for a User Information about Password Management Data Encryption Encryption: Random Key Generation Summary Exercises Oracle Utilities and Managing Data 21-1 Chapter Overview Oracle Utilities The Export Utility Export Modes Export Parameters Export Parameters (continued) Export Parameters (continued) Export Examples Import Utility Executing the Import Utility Import Parameters Import Parameters More on the Import Utility Rebuilding a Database Logical Backups Using Multiple Export Dump Files Using a Query Filter on Export Exporting Outlines Transportable Tablespaces Steps to Transport a Tablespace Technology Framers, LLC. xix All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

20 Self Containing Tablespaces New 9i Features in Oracle Utilities Exporting Statistics Importing Statistics New Parameters for Export and Import Tablespace Level Exports Direct-Load Inserts SQL*Loader SQL*Loader Files Conventional versus Direct Path Loads SQL*Loader Parameters The Control File Things to consider DBVERIFY Loadjava and Dropjava Review Questions Summary Exercises Creating an Oracle Instance and Database 22-1 Chapter Overview Preparation for Creating a Database Requirements for a Minimal Database Methods for Creating an Oracle Database Steps for Creating a Database Steps for Creating a Database Steps for Creating a Database (continued) Setup for UNIX Setup for NT Setup for NT (continued) Setup for NT (continued) Removing Oracle Servers and Software Removing Oracle Servers and Software (continued) Things to Consider When Creating a Database Optimal Flexible Architecture Follow OFA Guidelines Optimal Flexible Architecture Requirements Optimal Flexible Architecture Rules Example OFA Layout OFA Directory Layouts OFA Database Layouts File Naming Conventions The CREATE DATABASE Command CREATE DATABASE Example (Unix) CREATE DATABASE Example (Windows) Creating a Oracle9i Database Script xx Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

21 What is Created? Preinstalled Users Preinstalled Roles After Database Creation Scripts run at Database Creation Time Additional Scripts run at Database Creation Time Managing PL/SQL Packages Troubleshooting Database Creation Review Questions Summary Exercises Technology Framers, LLC. xxi All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

22 xxii Oracle9i DBA Fundamentals I Technology Framers, LLC. All rights reserved. No part of this material may be reproduced without the express written permission from Technology Framers, LLC.

23 Understanding the Oracle9i Server Architecture Chapter Overview To manage, optimize, and troubleshoot an Oracle9i server environment, database administrators must have a solid understanding of the Oracle architecture. This chapter will introduce the major components that make up an Oracle system. The major components are covered in detail in following chapters. This chapter objective is to introduce students to the Oracle world. This chapter will not cover topics in depth. Students should sit back and just get a feel for the world of an Oracle database. Details will be covered in more depth in following chapters. At the end of this chapter, students will understand: Main components of the Oracle9i Server architecture Server concepts and terminology The difference between an Oracle instance and database Logical and Physical storage structures The benefits of different Oracle architectures The benefits of the Optimal Flexible Architecture 2004 ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-1

24 1-2 Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

25 Understanding the Oracle9i Server Architecture Responsibilities of a DBA Depending on the environment, an Oracle database administrator (DBA) may be responsible for: Designing the logical and physical structures. Creating the instance and database for an Oracle Server. Managing users and security. Managing storage and growth. Performance tuning the Oracle Server. Backup and recovery. Network administration. Disaster recovery planning. Capacity planning and benchmarking. Supporting applications (performance tuning SQL statements and applications). Everything that can be addressed in your job description under other duties as will be assigned. Notes A DBA may have different responsibilities depending upon the company, type of database, and the position. Most DBAs are responsible for several of the tasks listed above. A number of trends are impacting DBAs: Databases are growing significantly in size, complexity, and utilization. 700 GB databases and larger with full time Internet activity are now common. DBAs have to manage a much larger number of users as Internet databases become more popular (thousands - millions of users), including large activity spikes. Databases have to run in a full time environment, support more users worldwide and in different time zones. It is becoming common to have data stored in non-traditional relational datatypes (pictures, maps, digital signatures, legal documents, chemical structures, etc.) 2004 ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-3

26 Changing DBA Environments Environments that DBAs work in are also changing significantly. Large corporations are looking at using smaller production DBA teams to manage critical areas such as tuning, storage and backup/recovery. The projects are using more application DBAs to support users, security, application development, etc. More development teams are working with application DBAs versus the traditional production DBA teams used years ago. In the past organizations had a tendency to throw hardware at performance problems. Organizations are now trying to do more with less and are requiring DBAs to be more resourceful in addressing tuning issues. Large companies are trying to leverage junior DBAs and minimize the costs of senior DBAs. More 3 rd party software is being used to help junior level DBAs manage Oracle systems. Software companies such as CA, Quest, BMC, etc. offer enterprise management and development suites for Oracle. Beginning in Oracle9iR2, the Oracle Enterprise Manager (OEM) is becoming a strong tool for Oracle database management. Previous releases of OEM were not robust enough. Older versions of Oracle used client/server solutions. Today more and more companies are looking at n-tier solutions with application servers. Client server is dying it just does not know it. More Oracle development shops are using Java and XML versus the traditional environments of PL/SQL, C, PowerBuilder, Forte, Oracle Forms, etc. 1-4 Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

27 Understanding the Oracle9i Server Architecture Managing Different Types of Databases Today's DBAs are often responsible for managing multiple databases. These databases can fall into different types and categories. A Data Warehouse is a type of Decision Support System (DSS). These systems: Typically load large volumes of data and then perform complex queries. Very few if any DML transactions are executed. Are denormalized for performance. Data accuracy and response time of large reports are primary issues. Large sorts are usually performed on the data. A data mart is a subset of a data warehouse. The data in a data mart is usually divided based upon business unit, geographical area, product line, etc. Online Analytical Processing (OLAP) is a multidimensional database that is used to perform complex analysis of the data. An Online Transaction Processing (OLTP) is more of a transaction-based system. These systems: Typically perform numerous small DML transactions with concurrent users. Data availability, concurrency, speed and recovery are primary issues. Hybrid systems are some combination of DSS and OLTP systems. Production systems are live systems being accessed by users. Ideally no development is occurring on these systems. The production database can be a different version of Oracle than the test and development databases. Test systems are used to validate new software versions, security implementations and features. Benchmarking and capacity planning are also performed on test systems. Ideally test systems are created by cloning the production systems. Development systems are used by programmers and DBAs for the development of new applications and software components ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-5

28 What is an Oracle Server? An Oracle server is an Object-Relational OLAP database management system. Made up of an instance and a database. An Oracle instance contains memory structures and background processes that maintain the state of the server. An Oracle database contains the physical files that hold all information for the Oracle system. The Oracle Database Administrator (DBA) is responsible for configuring, managing, maintaining, and tuning an Oracle server. There can be specialization in the following areas: (Tuning, Security, Backup/Recovery, Application, Storage, Real Application Clusters, Java, Replication, Shared Server Architecture, and Application Server). A session connection is established between a user process and an Oracle server. A Server Process manages the communication between the user process and the Oracle Server. Notes A user can log into the host operating system and then execute an application or tool that establishes a connection to the Oracle server (single or two-task architecture). A user can start an application or tool on a separate computer from the Oracle server. Network software establishes a connection with the Oracle server (client-server architecture). A listener process must be up and running on the Oracle server platform to recognize the network connection. Oracle supports Net8, IIOP, and HTTP listeners. A user can start an application or tool on a local machine and then establish a connection with a middle-tier server. The middle-tier server (i.e. Oracle9i Application Server Release 2) then connects to the Oracle server over a network connection (3-tier architecture). 1-6 Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

29 Understanding the Oracle9i Server Architecture Oracle Versioning An Oracle version can contain up to five numbers: Version number New features release number Patch set number Platform specific patch-set number Maintenance release number Recent major Oracle Releases: Oracle 7.3 (Relational) No longer supported at end of year 2000 Oracle 8.0 (Object-relational) Released is the terminal release. The Oracle8i (Internet platform) 8i Release 1 (8.1.5) i Release 2 (8.1.6) i Release 3 (8.1.7) 2000, 8i Release 3 ( ) 2001, ( spring 2001) Oracle 9i Release 1 (8.2) - (ebusiness Release) Released August of i was initially intended to be 8.2 but was too large to be considered a new features release Oracle 9i Release2 (Object-Relational OLAP database) Released May Oracle10G was released in the fall of ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-7

30 Server Architectural Overview The following diagram highlights the primary components found in Oracle servers. 1-8 Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

31 Understanding the Oracle9i Server Architecture Operating System Environment The following operating system environment variables must be set to run an Oracle system. These are the minimum parameters necessary to connect to an Oracle Instance. The ORACLE_HOME contains the directory path where the Oracle software is installed. ORACLE_HOME has subdirectories containing Oracle software and products. Example: /app/oracle/product/ The ORACLE_SID is the unique identifier for the Oracle instance. Example: fin, orcl, db1. An operating system variable PATH must include the $ORACLE_HOME/bin directory. The bin directory contains the Oracle executable programs. Notes Optional environmental variables include ORACLE_BASE and ORA_NLS33. ORACLE_BASE is recommended for OFA compliant systems (example: /app/oracle). ORA_NLS33 must be set if the character set USA7ASCII is not used. UTF8 is often used for databases that need to support globalization. Additional environmental parameters can be set to configure an Oracle environment. For example, the CLASSPATH variable needs to be set for the Oracle9i JVM. Check your installation manual if you are installing additional features beyond the core Oracle database. To customize a DBA environment for SQL*Plus, set the SQLPATH variable ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-9

32 Important Subdirectories in ORACLE_HOME The following list contains some of the important subdirectories below ORACLE_HOME. Be aware there are slight naming differences between operating systems. Directory admin Apache bin Classes dbs doc lib install jar javavm jdbc jlib jsp ldap network oci plsql rdbms/admin sqlj sqlplus xdk Description Administration directory for instance administration files Files supporting the HTTP Apache Web server Contains all Oracle executables Files containing Java classes Contains initialization file scripts and sql.bsq script Documentation readme files Product libraries Installation programs and files Java jar files Files for the Oracle9i JVM (renamed to Enterprise Java Engine) Files supporting Java Database Connectivity Java class libraries supporting EWT, Swing, Java Server Pages Files supportingoracle9i s Lightweight Directory Access Protocol Oracle Network product files C programming API s supporting the Oracle Call Interface PL/SQL environment Administration scripts and files SQLJ environment for embedded Java SQL*plus environment Files supporting the XDK environment Notes APIs are Application Programming Interfaces Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

33 Understanding the Oracle9i Server Architecture Oracle Product Subdirectories Each product subdirectory also contains a number of subdirectories. Some of the product subdirectories are: admin, demo, doc, install, lib, mesg, and log New product directories supporting the Internet platform include: Apache, classes, jar, javavm, jdbc, jlib, jsp, ldap, oo40, sqlj, xdk With Oracle s Universal Installer (Java-based GUI), there is now a much more consistent layout of the Oracle software directories across multiple platforms (Solaris, Linux, AIX, HP, Compaq Tru64, XP/Windows 2000/NT, etc.). DBAs should begin moving away from the traditional orainst program and begin using the Oracle Universal Installer. Exercise The Universal Installer can install and remove products similarly to orainst but with more functionality and flexibility. Since orainst and the Oracle Universal installer both use different audit and log files, it is not recommended to use both. Use the exercises at the end of this chapter to help get familiar with the Oracle environment for this classroom. They can be done now or they can wait till the end of the chapter ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-11

34 Oracle Instance Components System Global Area (SGA) is the area of shared memory allocated during startup to maintain information about the current state of the Oracle server. The SGA shared memory is divided into the following areas: Database buffer caches. Redo log cache. Shared pool area. Large pool (recommended if using Shared Server Architecture, Parallel Query, or Recovery Manager). Java pool area (used for Java stored procedures). The main (standard) Oracle background processes are: SMON, PMON, DBWR, LGWR, RECO, ARCH, CKPT, and Listener. The Oracle instance is the combination of the SGA shared memory and background processes. Notes A database (physical files) maps to a single instance unless the system is running a parallel server environment. The Real Application Cluster (RAC) has an INSTANCE_NAME and a SERVICE_NAME for identification. An Oracle system contains server processes. Server processes execute the code for a user process. These server processes manage the connectivity between user processes and the instance. A user process executes the code of an application program accessing an Oracle server. User processes are usually applications or Oracle tools. Example user processes include Oracle Forms, C programs, Visual Basic, Powerbuilder, SQL*Plus, and Oracle Enterprise Manager (OEM). Every Oracle instance has a unique identifier defined by the operating system variable ORACLE_SID Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

35 Understanding the Oracle9i Server Architecture Database Files An Oracle database is made up of different types of files. The file types listed below are the minimum (and we do mean bare minimum) files required to define a database: An initialization file contains the Oracle system variables and their definitions. These definitions determine the configuration at startup. One control file is needed to maintain the mapping of all external files and the internal state of the system. At least one data file (system datafile) is required to bring up an Oracle system. This system datafile will contain all of the system tables. The system tables maintain all information about the database. A minimum of two redo log groups is necessary to manage system changes. A redo log group is made up of one or more redo log files. Notes A simple Oracle database can be brought online with the above minimum configuration. This minimum configuration should only be used as a base configuration. The init.ora file is also referred to as the p-file, initialization, or parameter file. The control file contains the necessary information to maintain database integrity. The system data file contains the system tables. These tables contain the data dictionary (database metadata), privileges, before-image information, and schema data. The redo log files maintain information about all changes made to the database. This information is used to help rebuild the database in case of failure. Additional files that are often used in Oracle databases include archived redo log files and a password file. The archived redo log files contain off-line copies of previous changes made to a system. The password file is used for authentication of users with special privileges. Every database has a unique identifier defined by the DB_NAME variable. This variable is defined in the init.ora configuration file. The ORACLE_SID and the DB_NAME are usually the same name for a single instance environment ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-13

36 Control Files Every database must have at least one control file. The control file maintains information about the database. The control file maintains information about the: Names and physical mapping and names of all data files and online redo log files. Database name and the database creation date and time. Current log sequence number and checkpoint information. The initialization parameter CONTROL_FILES defines the location and names of all control files. If more than one control file is listed with the CONTROL_FILES parameter, the files will be multiplexed (mirrored). Initialization file: CONTROL_FILES = /oradata/fin/disk1/control_ord01.ctl, /oradata/fin/disk2/control_ord02.ctl Notes Control Files: The control file is created when the database is created. It is highly recommended to have a minimum of two control files, on separate disks with every database The size of the control files is relatively small. For this reason, most DBAs prefer to have three or four control files defined for a database. Checkpoints: When a checkpoint occurs, Oracle writes all data changes to the data files to keep the data files and the redo log files synchronized. When a redo log group fills up and Oracle switches to the next redo log group a checkpoint occurs. Checkpoints will be covered in more detail in a following chapter Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

37 Understanding the Oracle9i Server Architecture Redo Log Files An Oracle database records all changes made to data. These changes are stored in redo log files. Redo log files are used to recover the database in case of media (disk) failure. The LGWR process writes data changes from the redo log cache to the files in the current redo log group. Redo log files are organized into redo log groups. A redo log group is a collection of mirrored redo log files. Every redo log file in a group is a mirror of the other files in the group. For each committed transaction, the LGWR process will write the changes to every redo log file in the current redo log group. When a transaction is committed: The LGWR process will read the redo entries from the log buffer and write them to the redo log files (fast commit). A unique number called the System Change Number (SCN) will be generated for each committed transaction. Notes A database must have a minimum of two redo log groups. Each redo log group can have multiple log file members that are mirrored by Oracle. A typical database will have 20 redo log groups or more. Mirroring redo log file members is highly recommended. The redo log files tied to an instance are referred to as a thread of redo log files. Most instances have a single thread of redo log files. A Real Application Cluster (RAC) environment has multiple threads of redo log files. The RAC is an Oracle system running multiple instances connected to a single database (beyond scope of this course) ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-15

38 Redo Log Files (continued) The information in the redo log files is used to recover an Oracle system in case of failure. All redo log groups are written to in a circular fashion. Scenario for two log groups: One of the groups will be the current redo log group. The log files for the current group are written to sequentially until full. When the log files are full for a redo log group, Oracle will perform a log switch and begin writing to the next redo log group. A log switch can be performed manually with the ALTER SYSTEM SWITCH LOGFILE command. When the next redo log group fills up, Oracle will, again, perform a log switch and start writing over the files in the first redo log group. A log sequence number is generated for every redo log file in a group during a log switch (look at the ARCHIVE_LOG_FORMAT parameter or the ARCHIVE LOG LIST command). The log sequence number is used to identify redo log files in a group. Since all redo log files in a group are mirrored, each redo log file in a group will have the same log sequence number. Notes When the DBWR process cleans the dirty data buffers in the database buffer cache by writing them to the data files, a checkpoint occurs. Checkpoints synchronize the data files and redo log files to minimize the time required to perform instance recovery. A checkpoint also occurs when the redo log files in a group fills up or the ALTER TABLESPACE SYSTEM BEGIN BACKUP command is executed during a hot backup. (Checkpoints are covered in detail in a following chapter.) The redo log files belonging to a single instance are referred to as a thread of redo log files Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

39 Understanding the Oracle9i Server Architecture Logical Storage Structures A data block is made up of a specific number of bytes. An extent is a number of contiguous data blocks acquired in a single allocation. A segment is a logical grouping of extents allocated for a specific database object (data, index, rollback, temporary). A tablespace is a logical storage unit used to group logical structures (schemas) together. A tablespace can span multiple data files in the database. Each database user has an associated schema. A schema is the collection of logical structures which the user owns. Schema objects: Include tables, views, procedures, functions, packages, synonyms, sequences, clusters and database links. Give users access to the database information ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-17

40 Oracle Block Sizes An Oracle9i database supports a standard block size and up to four additional block sizes. The standard database block size is defined at database creation time with the DB_BLOCK_SIZE in the initialization file. The default data block size (e.g. 8KB) for the specific operating system will be used if DB_BLOCK_SIZE is not defined. Once the database is created, the standard block size cannot be changed. It is recommended to make the Oracle block size a multiple of the operating system block size (i.e. 2K, 4K 32K). It is a little early to begin discussing multiple block sizes. The rest of the chapter will focus on core concepts. Managing multiple block sizes will be covered in depth later in the course. Notes Oracle began supporting multiple block sizes in a database with Oracle9i Release Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC

41 Understanding the Oracle9i Server Architecture Blocks, Extents, and Segments Oracle manages data in storage units called data blocks. Oracle performs I/O operations in block size units. Oracle reads blocks not records. Relationship between blocks, extents and segments: Notes The minimum and maximum Oracle block size depends on the operating system. The Oracle block size has a significant impact on performance and storage efficiency. Properly setting the physical characteristics of extents and blocks can have a significant impact on performance (covered later). When most data operations involve a few records (OLTP systems), the block size should be smaller (i.e. 4k or 8k block sizes). When a large number of records are accessed on a regular basis (DSS) the block size should be larger (16k or 32k block sizes) ITCourseware, LLC Understanding the Oracle9i Server Architecture 1-19

42 Different Types of Segments A data segment stores data. The different types of data segments include: Regular, partitioned, clustered and global temporary data segments. An index segment stores the indexed values along with the physical address (rowid) where the indexed value can be found. Regular, bit-mapped, reverse, partitioned, and IOT index segments. An undo segment stores before-image data. Every block modified with an insert, update, or delete is stored in an undo segment. Undo segments replaced rollback segments beginning in 9i. A temporary (sort) segment is used as a workspace area for SQL commands performing sorts during execution. A temporary segment is used to store sorting information if there is not enough room in memory (determined by SORT_AREA_SIZE). Notes A segment is put in a specific tablespace. Extents are allocated as data is added to the segment. The extents may or may not be contiguous. The blocks inside of extents are contiguous. A DBA should separate data, index, rollback, and temporary segments into separate storage areas. Segments containing extents of similar sizes should be stored together. Storing extents of different sizes in the same tablespace greatly increases the probability of fragmentation. Segments can span multiple data files. Extents and data blocks cannot span a physical data file. Different type segments or segments of different life spans should not be stored in the same tablespace. A global temporary data segment is similar but different than a temporary sort segment (trying to create excitement and curiosity for later in the course) Oracle9i DBA Fundamentals I 2004 ITCourseware, LLC