Oracle Database Concepts 10g Release 2 B14220.pdf

Oracle® Database

Concepts

10 g Release 2 (10.2)

B14220-02

October 2005

Oracle Database Concepts, 10 g Release 2 (10.2)

B14220-02

Primary Author: Michele Cyran

Contributing Author: Paul Lane, JP Polk

Contributor: Omar Alonso, Penny Avril, Hermann Baer, Sandeepan Banerjee, Mark Bauer, Bill Bridge,

Sandra Cheevers, Carol Colrain, Vira Goorah, Mike Hartstein, John Haydu, Wei Hu, Ramkumar Krishnan,

Vasudha Krishnaswamy, Bill Lee, Bryn Llewellyn, Rich Long, Diana Lorentz, Paul Manning, Valarie Moore,

Mughees Minhas, Gopal Mulagund, Muthu Olagappan, Jennifer Polk, Kathy Rich, John Russell, Viv

Schupmann, Bob Thome, Randy Urbano, Michael Verheij, Ron Weiss, Steve Wertheimer

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Contents

Preface ............................................................................................................................................................. xxv

Audience................................................................................................................................................... xxv

Documentation Accessibility ................................................................................................................. xxv

Related Documentation .......................................................................................................................... xxvi

Conventions ............................................................................................................................................. xxvi

Part I What Is Oracle?

1 Introduction to the Oracle Database

Oracle Database Architecture ............................................................................................................... 1-1

Overview of Oracle Grid Architecture............................................................................................ 1-2

Grid Computing Defined........................................................................................................... 1-2

Grid Computing in Oracle Database 10 g ................................................................................. 1-5

Overview of Application Architecture ........................................................................................... 1-7

Client/Server Architecture........................................................................................................ 1-7

Multitier Architecture: Application Servers ........................................................................... 1-7

Overview of Physical Database Structures..................................................................................... 1-8

Datafiles ....................................................................................................................................... 1-8

Control Files................................................................................................................................. 1-8

Redo Log Files ............................................................................................................................. 1-9

Archive Log Files ........................................................................................................................ 1-9

Parameter Files ............................................................................................................................ 1-9

Alert and Trace Log Files ........................................................................................................... 1-9

Backup Files .............................................................................................................................. 1-10

Overview of Logical Database Structures ................................................................................... 1-10

Tablespaces ............................................................................................................................... 1-10

Oracle Data Blocks ................................................................................................................... 1-10

Extents ....................................................................................................................................... 1-11

Segments ................................................................................................................................... 1-11

Overview of Schemas and Common Schema Objects ............................................................... 1-12

Tables ......................................................................................................................................... 1-12

Indexes ...................................................................................................................................... 1-12

Views ......................................................................................................................................... 1-12

Clusters ...................................................................................................................................... 1-13

Synonyms .................................................................................................................................. 1-13

iii

Overview of the Oracle Data Dictionary ..................................................................................... 1-13

Overview of the Oracle Instance................................................................................................... 1-13

Real Application Clusters: Multiple Instance Systems....................................................... 1-13

Instance Memory Structures ................................................................................................. 1-14

System Global Area ................................................................................................................. 1-14

Program Global Area............................................................................................................... 1-15

Oracle Background Processes ................................................................................................ 1-15

Process Architecture ................................................................................................................ 1-15

Overview of Accessing the Database ........................................................................................... 1-16

Network Connections.............................................................................................................. 1-16

Starting Up the Database ........................................................................................................ 1-16

How Oracle Works ................................................................................................................. 1-17

Overview of Oracle Utilities .......................................................................................................... 1-17

Oracle Database Features .................................................................................................................... 1-17

Overview of Scalability and Performance Features ................................................................... 1-18

Concurrency ............................................................................................................................. 1-18

Read Consistency .................................................................................................................... 1-18

Locking Mechanisms .............................................................................................................. 1-19

Quiesce Database ..................................................................................................................... 1-20

Real Application Clusters ....................................................................................................... 1-20

Portability.................................................................................................................................. 1-20

Overview of Manageability Features ........................................................................................... 1-21

Self-Managing Database ......................................................................................................... 1-21

Oracle Enterprise Manager..................................................................................................... 1-21

SQL*Plus.................................................................................................................................... 1-21

Automatic Storage Management ........................................................................................... 1-21

The Scheduler ........................................................................................................................... 1-22

Database Resource Manager ................................................................................................. 1-22

Overview of Database Backup and Recovery Features............................................................. 1-22

Types of Failures ..................................................................................................................... 1-22

Structures Used for Recovery ................................................................................................ 1-23

Overview of High Availability Features...................................................................................... 1-24

Overview of Business Intelligence Features................................................................................ 1-25

Data Warehousing ................................................................................................................... 1-25

Extraction, Transformation, and Loading (ETL) ................................................................. 1-25

Materialized Views .................................................................................................................. 1-25

Bitmap Indexes in Data Warehousing .................................................................................. 1-26

Table Compression .................................................................................................................. 1-26

Parallel Execution .................................................................................................................... 1-26

Analytic SQL............................................................................................................................. 1-26

OLAP Capabilities ................................................................................................................... 1-26

Data Mining .............................................................................................................................. 1-27

Partitioning ............................................................................................................................... 1-27

Overview of Content Management Features .............................................................................. 1-27

XML in Oracle........................................................................................................................... 1-27

LOBs........................................................................................................................................... 1-27

Oracle Text ............................................................................................................................... 1-28

Oracle Ultra Search ................................................................................................................. 1-28

Oracle inter Media..................................................................................................................... 1-28

Oracle Spatial............................................................................................................................ 1-28

Overview of Security Features ...................................................................................................... 1-28

Security Mechanisms .............................................................................................................. 1-29

Overview of Data Integrity and Triggers .................................................................................... 1-29

Integrity Constraints................................................................................................................ 1-30

Keys ........................................................................................................................................... 1-30

Triggers ..................................................................................................................................... 1-30

Overview of Information Integration Features........................................................................... 1-31

Distributed SQL ...................................................................................................................... 1-31

Oracle Streams ......................................................................................................................... 1-31

Oracle Transparent Gateways and Generic Connectivity ................................................. 1-33

Oracle Database Application Development ................................................................................... 1-33

Overview of Oracle SQL ................................................................................................................ 1-33

SQL Statements ........................................................................................................................ 1-33

Overview of PL/SQL...................................................................................................................... 1-34

PL/SQL Program Units .......................................................................................................... 1-35

Overview of Java ............................................................................................................................. 1-35

Overview of Application Programming Languages (APIs) ..................................................... 1-35

Overview of Transactions .............................................................................................................. 1-36

Commit and Undo Transactions............................................................................................ 1-37

Savepoints ................................................................................................................................. 1-37

Overview of Datatypes................................................................................................................... 1-37

Overview of Globalization ............................................................................................................ 1-38

Part II Oracle Database Architecture

2 Data Blocks, Extents, and Segments

Introduction to Data Blocks, Extents, and Segments ........................................................................ 2-1

Overview of Data Blocks ........................................................................................................................ 2-3

Data Block Format ............................................................................................................................. 2-3

Header (Common and Variable) .............................................................................................. 2-4

Table Directory ............................................................................................................................ 2-4

Row Directory ............................................................................................................................. 2-4

Overhead ...................................................................................................................................... 2-4

Row Data ...................................................................................................................................... 2-4

Free Space..................................................................................................................................... 2-4

Free Space Management.................................................................................................................... 2-4

Availability and Optimization of Free Space in a Data Block .............................................. 2-5

Row Chaining and Migrating .................................................................................................. 2-5

PCTFREE, PCTUSED, and Row Chaining .................................................................................... 2-6

The PCTFREE Parameter ........................................................................................................... 2-6

The PCTUSED Parameter .......................................................................................................... 2-7

Overview of Extents .............................................................................................................................. 2-10

When Extents Are Allocated ........................................................................................................ 2-10

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