Tài liệu Oracle Performance Tuning for 10gR2, Second Edition pptx

i

Oracle

Performance Tuning

and Optimization

Edward Whalen

201 West 103rd Street

Indianapolis, Indiana 46290

®

ii

Oracle Performance Tuning & Optimization

Publisher and President: Richard K. Swadley

Acquisitions Manager: Greg Wiegand

Development Manager: Dean Miller

Managing Editor: Cindy Morrow

Marketing Manager: Gregg Bushyeager

To my father.

Copyright ” 1996 by Sams Publishing

FIRST EDITION

All rights reserved. No part of this book shall be reproduced, stored in a retrieval

system, or transmitted by any means, electronic, mechanical, photocopying,

recording, or otherwise, without written permission from the publisher. No patent

liability is assumed with respect to the use of the information contained herein.

Although every precaution has been taken in the preparation of this book, the

publisher and author assume no responsibility for errors or omissions. Neither is any

liability assumed for damages resulting from the use of the information contained

herein. For information, address Sams Publishing, 201 W. 103rd St., Indianapolis,

IN 46290.

International Standard Book Number: 0-672-30866-X

Library of Congress Catalog Card Number: 95-72345

99 98 97 96 4 3 2 1

Interpretation of the printing code: the rightmost double-digit number is the year of

the book’s printing; the rightmost single-digit, the number of the book’s printing.

For example, a printing code of 96-1 shows that the first printing of the book

occurred in 1996.

Composed in AGaramond and MCPdigital by Macmillan Computer Publishing

Printed in the United States of America

All terms mentioned in this book that are known to be trademarks or service marks

have been appropriately capitalized. Sams Publishing cannot attest to the accuracy of

this information. Use of a term in this book should not be regarded as affecting the

validity of any trademark or service mark.

Acquisitions Editor

Rosemarie Graham

Development Editors

Byron Pearce

Todd Bumbalough

Software Development

Specialist

Steve Flatt

Production Editor

Alice Martina Smith

Technical Reviewers

David Kennedy

Stephen Tallon

Editorial Coordinator

Bill Whitmer

Technical Edit Coordinator

Lynette Quinn

Formatter

Frank Sinclair

Editorial Assistants

Sharon Cox

Andi Richter

Rhonda Tinch-Mize

Cover Designer

Tim Amrhein

Book Designer

Alyssa Yesh

Copy Writer

Peter Fuller

Production Team Supervisor

Brad Chinn

Production

Mary Ann Abramson

Georgianna Briggs

Jama Carter

Amy Chinn

Michael Dietsch

Jason Hand

Sonja Hart

Ayanna Lacey

Clint Lahnen

Paula Lowell

Brian-Kent Proffitt

Bobbi Satterfield

Susan Van Ness

Colleen Williams

iii

Overview

Introduction ............................................................................................ xxiv

PART I Introduction 1

1 Introduction to Oracle ................................................................................. 3

2 Understanding Terms ................................................................................ 21

3 What Is a Well-Tuned System? .................................................................. 31

4 Tuning Methodology ................................................................................. 41

5 Benchmarking ........................................................................................... 51

6 Performance Monitoring Tools.................................................................. 73

7 Performance Engineering Starts at the Design Stage ................................... 81

PART II Tuning the Server 89

8 What Affects Oracle Server Performance? ...................................................91

9 Oracle Instance Tuning.............................................................................. 97

10 Performance Enhancements .................................................................... 139

11 Tuning the Server Operating System........................................................ 167

12 Operating System-Specific Tuning .......................................................... 177

13 System Processors .................................................................................... 205

14 Advanced Disk I/O Concepts .................................................................. 213

15 Disk Arrays ..............................................................................................225

PART III Configuring the System 243

16 OLTP System.......................................................................................... 245

17 Batch Processing System........................................................................... 265

18 Decision Support System ......................................................................... 285

19 Data Warehousing System........................................................................303

20 BLOB System.......................................................................................... 323

21 The Oracle Parallel Server System ............................................................ 339

22 Optimal Backup and Recovery ................................................................ 349

23 Miscellaneous Configurations .................................................................. 367

PART IV Tuning SQL 391

24 What Is a Well-Tuned SQL Statement? ................................................... 393

25 Using EXPLAIN PLAN and SQL Trace ......................................................... 403

26 Tuning SQL Statements........................................................................... 419

27 Using the Oracle Optimizer .................................................................... 437

28 Using Procedures, Functions, and Packages ............................................. 449

29 Providing for Data Integrity and Triggers.................................................461

30 Using Hints..............................................................................................475

31 Introducing SQL Development Tools ...................................................... 489

32 Miscellaneous SQL Topics .......................................................................501

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Oracle Performance Tuning & Optimization

PART V Tuning the Client 513

33 What Affects Client Performance? ........................................................... 515

34 Tuning the Client System ........................................................................525

35 Using GUI Builders ................................................................................. 533

36 Using Middleware Products .................................................................... 555

PART VI Tuning the Network 563

37 What Affects Network Performance?........................................................ 565

38 Tuning the Network Components ........................................................... 573

PART VII References 579

A Review of Tuning Guidelines .................................................................. 581

B Quick Reference ...................................................................................... 595

C Flowcharts ................................................................................................ 603

D Glossary ................................................................................................... 607

E Oracle Tuning Parameters ........................................................................619

F Contents of the CD-ROM .......................................................................645

Index ....................................................................................................... 649

v

Contents

Introduction....................................................................................... xxiv

Part I Introduction 1

1 Introduction to Oracle ............................................................................ 3

The Database .............................................................................................. 4

The Physical Layer .................................................................................. 4

The Logical Layer .................................................................................... 5

The Oracle Instance ..................................................................................... 8

The Oracle Memory Structure ................................................................ 8

System Global Area (SGA) ...................................................................... 9

Program Global Area (PGA) ................................................................. 10

Processes ................................................................................................10

How Transactions Work ............................................................................ 12

Oracle Products ......................................................................................... 13

Oracle RDBMS Products...................................................................... 13

Oracle Workgroup Server ..................................................................... 15

Personal Oracle for Windows ................................................................ 16

Oracle Development Tools ................................................................... 16

Oracle Applications ............................................................................... 17

Oracle Services ...................................................................................... 18

Summary.................................................................................................... 19

2 Understanding Terms ........................................................................... 21

Terms ........................................................................................................ 22

RDBMS Functionality ............................................................................... 26

Checkpoint ........................................................................................... 26

Logging and Archiving........................................................................... 26

Business Models ........................................................................................ 27

OnLine Transaction Processing (OLTP) ............................................... 27

Batch Processing.................................................................................... 27

Decision Support .................................................................................. 28

Data Warehousing................................................................................. 28

Binary Large Objects (BLOBs) .............................................................. 28

Unit Conversions....................................................................................... 28

Powers of 10 ......................................................................................... 29

Storage Units ........................................................................................ 29

Summary.................................................................................................... 30

3 What Is a Well-Tuned System? .............................................................31

Client/Server Computing ........................................................................... 32

The Client or Front-End Machines ....................................................... 33

The Server ............................................................................................ 33

The Network ........................................................................................ 35

Client/Server Checklist ..........................................................................35

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Oracle Performance Tuning & Optimization

Host-Based Computing.............................................................................. 36

The Front-End Application................................................................... 36

The Database ........................................................................................ 36

Terminal-Based Checklist ..................................................................... 37

Batch Computing ...................................................................................... 38

Batch-Processing Checklist.................................................................... 39

Exceptions .................................................................................................. 39

Multimedia Systems .............................................................................. 39

Shipping Systems .................................................................................. 39

Summary.................................................................................................... 40

4 Tuning Methodology ............................................................................ 41

Goals ......................................................................................................... 42

Throughput .......................................................................................... 42

Response Time ...................................................................................... 42

Connectivity ......................................................................................... 43

Fault Tolerance ..................................................................................... 43

Load Time ............................................................................................ 44

Tuning Methodology ................................................................................. 44

Examine the Problem ............................................................................ 45

Determine the Problem .........................................................................47

Determine the Solution and Set Goals ...................................................48

Test the Solution ................................................................................... 49

Analyze the Results ................................................................................ 50

Summary.................................................................................................... 50

5 Benchmarking ....................................................................................... 51

Introduction to Benchmarking .................................................................. 52

Industry Standard Benchmarks .................................................................. 52

The Transaction Processing Performance Council (TPC) ..................... 53

TPC Rules and Regulations .................................................................. 55

Results ................................................................................................... 56

Benchmarks .......................................................................................... 57

Publication Benchmarks ............................................................................. 69

Custom Benchmarks .................................................................................. 70

Writing Your Own Benchmark ............................................................. 70

Summary.................................................................................................... 72

6 Performance Monitoring Tools .............................................................73

Oracle Tools ...............................................................................................75

SQL*DBA Monitor ............................................................................... 76

Server Manager ..................................................................................... 76

Oracle SNMP Agents ............................................................................ 76

SQL Trace ............................................................................................ 76

EXPLAIN PLAN ......................................................................................... 77

vii

Contents

OS Tools.................................................................................................... 77

Third-Party Tools ...................................................................................... 78

Real-Time Monitors .............................................................................. 79

Threshold Monitors .............................................................................. 79

Summary.................................................................................................... 80

7 Performance Engineering Starts at the Design Stage ............................ 81

Design Stage...............................................................................................82

Database Layout .................................................................................... 82

Indexes and Clusters .............................................................................. 83

Application Design ................................................................................ 83

Hardware Sizing .................................................................................... 83

Network Considerations ........................................................................84

Performance Tuning after the System Is Built............................................ 84

Tuning the Client ................................................................................. 85

Tuning the Server.................................................................................. 85

Tuning the Network.............................................................................. 85

Summary.................................................................................................... 86

Part II Tuning the Server 89

8 What Affects Oracle Server Performance? ............................................ 91

System Bottlenecks .................................................................................... 92

Finding the Bottleneck ..........................................................................92

Removing the Bottleneck ...................................................................... 93

System Tuning .......................................................................................... 93

Tuning RDBMS Resources ................................................................... 93

Tuning OS Resources ............................................................................ 94

Tuning Hardware Resources ................................................................. 94

Other Tuning Factors ............................................................................ 95

System Limitations .................................................................................... 95

Summary.................................................................................................... 95

9 Oracle Instance Tuning ......................................................................... 97

Tuning Memory ........................................................................................ 98

Tuning the Operating System ............................................................... 99

Tuning the Private SQL and PL/SQL Areas ........................................ 100

Tuning the Shared Pool .......................................................................100

Tuning the Buffer Cache .................................................................... 107

Tuning the I/O Subsystem .......................................................................108

Understanding Disk Contention ......................................................... 109

Identifying Disk Contention Problems ................................................110

Solving Disk Contention Problems...................................................... 111

Reducing Unnecessary I/O Overhead....................................................... 117

Migrated and Chained Rows ............................................................... 117

Dynamic Extensions ............................................................................ 118

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Oracle Performance Tuning & Optimization

PCTFREE and PCTUSED Command Options ............................................ 119

A Review of I/O Reduction Techniques.............................................. 122

Tuning Rollback Segments .......................................................................123

Understanding How Rollback Segments Work ................................... 123

Tuning Rollback Segments ................................................................. 126

Review of Rollback Segment Tuning ................................................... 130

Checking for Latch Contention ............................................................... 130

Redo Log Buffer Contention............................................................... 130

Redo Log Buffer Latch Contention ..................................................... 131

Tuning Checkpoints ................................................................................ 133

Optimizing Archiving .............................................................................. 134

Adjusting the Effect of Archiving......................................................... 135

Optimizing Sorts ..................................................................................... 135

Minimizing Free List Contention ............................................................ 136

Summary.................................................................................................. 137

10 Performance Enhancements ................................................................ 139

Block Size................................................................................................. 140

Clusters ............................................................................................... 141

Direct-Write Sorts ................................................................................... 143

Fragmentation ......................................................................................... 144

Hash Clusters .......................................................................................... 146

When To Hash ................................................................................... 147

Indexes ..................................................................................................... 148

Index Types ........................................................................................ 149

How the Oracle Index Works ............................................................. 149

What To Index ................................................................................... 150

Multiblock Reads..................................................................................... 152

Multiblock Writes ................................................................................... 152

Parallel Query Option .............................................................................. 153

Parallel Query Processing .................................................................... 153

Direct-Write Sorts ............................................................................... 158

Parallel Index Creation ........................................................................159

Parallel Loading................................................................................... 159

Parallel Recovery ................................................................................. 160

Parallel Server Option .............................................................................. 161

Spin Counts .............................................................................................164

Summary.................................................................................................. 164

11 Tuning the Server Operating System...................................................167

Goals ....................................................................................................... 168

Processes .................................................................................................. 169

Memory ................................................................................................... 170

I/O .......................................................................................................... 170

ix

Contents

Direct or Synchronous I/O ................................................................. 172

Asynchronous I/O ............................................................................... 172

Miscellaneous .......................................................................................... 173

Post-Wait Semaphore .......................................................................... 173

Scheduling and Preemption ................................................................ 173

Cache Affinity ..................................................................................... 174

Summary.................................................................................................. 174

12 Operating System-Specific Tuning ......................................................177

NetWare .................................................................................................. 178

Architectural Overview ........................................................................178

Tuning Considerations ........................................................................179

Windows NT .......................................................................................... 183

Architectural Overview ........................................................................183

Tuning Considerations ........................................................................185

OS/2 ........................................................................................................ 188

Architectural Overview ........................................................................188

Tuning Considerations ........................................................................188

UNIX ...................................................................................................... 191

Architectural Overview ........................................................................192

Tuning Considerations ........................................................................192

Summary.................................................................................................. 203

13 System Processors ............................................................................... 205

Overview of Computer Architecture ........................................................ 206

CPU and Cache .................................................................................. 206

CPU Design .............................................................................................207

CISC Processors .................................................................................. 207

RISC Processors .................................................................................. 208

Multiprocessor Systems ............................................................................ 209

SMP Systems ...................................................................................... 209

MPP Systems ...................................................................................... 209

CPU Cache ..............................................................................................210

System Memory Architecture .................................................................. 210

Virtual Memory System .......................................................................211

Bus Design ............................................................................................... 211

Summary.................................................................................................. 212

14 Advanced Disk I/O Concepts .............................................................. 213

Disk Operation........................................................................................ 214

Seek Time ................................................................................................ 216

Rotational Latency ................................................................................... 217

Data Transfer Rate................................................................................... 217

Queue Time .............................................................................................218

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Oracle Performance Tuning & Optimization

Disk Performance .................................................................................... 219

Random I/Os ...................................................................................... 220

Sequential I/Os ................................................................................... 220

Summary.................................................................................................. 223

15 Disk Arrays ......................................................................................... 225

How Does a Disk Array Work? ............................................................... 226

Software Array..................................................................................... 227

Hardware Array ................................................................................... 227

RAID Technology ................................................................................... 229

RAID-0 ............................................................................................... 230

RAID-1 ............................................................................................... 230

RAID-2 ............................................................................................... 231

RAID-3 ............................................................................................... 231

RAID-4 ............................................................................................... 232

RAID-5 ............................................................................................... 232

Fault-Tolerance Concerns ........................................................................233

No Data Protection ............................................................................. 233

Full Data Protection ............................................................................ 234

Partial Data Protection ........................................................................234

Configuring RAID for RDBMS Performance .......................................... 235

Isolate Sequential I/Os ......................................................................... 236

Distribute Random I/Os ......................................................................237

Size the Volume Properly .................................................................... 238

Configure for the Disk Array............................................................... 240

RAID Comparison .................................................................................. 240

Summary.................................................................................................. 241

Part III Configuring the System 243

16 OLTP System ...................................................................................... 245

Characteristics of the OLTP System......................................................... 246

Data Access Patterns ............................................................................ 246

System Load........................................................................................ 247

Goals ................................................................................................... 248

Design Considerations ............................................................................. 249

Physical Data Layout ........................................................................... 250

Hardware Considerations.................................................................... 253

Tuning Considerations ............................................................................ 253

Oracle Tuning..................................................................................... 254

Server OS Tuning ............................................................................... 255

Enhancements ......................................................................................... 256

Oracle Parallel Server Option .............................................................. 257

Hardware Enhancements .................................................................... 257

xi

Contents

Performance Verification .................................................................... 260

What To Test in the RDBMS ............................................................. 261

What To Test in the OS ......................................................................261

Benchmarks ........................................................................................ 262

Summary.................................................................................................. 262

17 Batch Processing System ..................................................................... 265

Characteristics of the Batch Processing System ........................................ 266

Data Access Patterns ............................................................................ 267

System Load........................................................................................ 267

Goals ................................................................................................... 268

Design Considerations ............................................................................. 270

Physical Data Layout ........................................................................... 270

Hardware Considerations.................................................................... 274

Tuning Considerations ............................................................................ 274

Oracle Tuning..................................................................................... 274

Server OS Tuning ............................................................................... 276

Enhancements ......................................................................................... 277

Parallel Query Option ......................................................................... 277

Oracle Parallel Server Option .............................................................. 278

Hardware Enhancements .................................................................... 279

Performance Verification .................................................................... 281

What To Test in the RDBMS ............................................................. 281

What To Test in the OS ......................................................................282

Benchmarks ........................................................................................ 282

Summary.................................................................................................. 283

18 Decision Support System .................................................................... 285

Characteristics of a DSS System ............................................................... 287

Data Access Patterns ............................................................................ 287

System Load........................................................................................ 288

Goals ................................................................................................... 289

Design Considerations ............................................................................. 290

Physical Data Layout ........................................................................... 291

Hardware Considerations.................................................................... 294

Tuning Considerations ............................................................................ 294

Oracle Tuning..................................................................................... 294

Server OS Tuning ............................................................................... 295

Enhancements ......................................................................................... 296

Parallel Query Option ......................................................................... 297

Oracle Parallel Server Option .............................................................. 297

Hardware Enhancements .................................................................... 298

Performance Verification .................................................................... 300

xii

Oracle Performance Tuning & Optimization

What To Test in the RDBMS ............................................................. 301

What To Test in the OS ......................................................................301

Benchmarks ........................................................................................ 301

Summary.................................................................................................. 302

19 Data Warehousing System .................................................................. 303

Characteristics of a Data Warehouse ........................................................ 304

Data Access Patterns ............................................................................ 305

System Load........................................................................................ 306

Goals ................................................................................................... 307

Design Considerations ............................................................................. 308

Physical Data Layout ........................................................................... 308

Fault Tolerance Consideration ............................................................ 311

Hardware Considerations.................................................................... 312

Tuning Considerations ............................................................................ 312

Oracle Tuning..................................................................................... 312

Server OS Tuning ............................................................................... 314

Enhancements ......................................................................................... 315

Parallel Query Option ......................................................................... 316

Oracle Parallel Server ........................................................................... 316

Hardware Enhancements .................................................................... 317

Performance Verification .................................................................... 319

What To Test in the RDBMS ............................................................. 320

What To Test in the OS ......................................................................320

Benchmarks ........................................................................................ 320

Summary.................................................................................................. 321

20 BLOB System...................................................................................... 323

Characteristics of BLOBs ......................................................................... 324

Data Access Patterns ............................................................................ 324

System Load........................................................................................ 324

Goals ................................................................................................... 325

Design Considerations ............................................................................. 327

Physical Data Layout ........................................................................... 328

Hardware Considerations.................................................................... 331

Tuning Considerations ............................................................................ 331

Oracle Tuning..................................................................................... 332

Server OS Tuning ............................................................................... 333

Enhancements ......................................................................................... 333

Hardware Enhancements .................................................................... 334

Performance Verification .................................................................... 335

What To Test in the RDBMS ............................................................. 336

What To Test in the OS ......................................................................336

Benchmarks ........................................................................................ 336

Summary.................................................................................................. 337

xiii

Contents

21 The Oracle Parallel Server System .......................................................339

Oracle Parallel Server Architecture ........................................................... 340

Design Considerations ............................................................................. 343

Design Goals ....................................................................................... 343

System Design ......................................................................................... 346

Tuning the Parallel Server System........................................................ 346

Summary.................................................................................................. 348

22 Optimal Backup and Recovery............................................................349

RDBMS Operational Review .................................................................. 351

Backup Process.................................................................................... 351

Recovery Process ................................................................................. 351

Characteristics of the Oracle Backup Process ........................................... 352

Cold (Offline) Backup ......................................................................... 352

Hot (Online) Backup .......................................................................... 352

Data Access Patterns During Backup ................................................... 353

System Load During Backup ............................................................... 353

Backup Goals ...................................................................................... 353

System Design Considerations ................................................................. 354

Cold Database Backup......................................................................... 354

Hot Database Backup .......................................................................... 355

Tuning Considerations ............................................................................ 358

System Enhancements To Improve Backup Performance ........................ 359

CPU Enhancements ............................................................................ 359

I/O Enhancements .............................................................................. 359

Network Enhancements.......................................................................360

Split Up the Backup ............................................................................ 360

Performance Verification .................................................................... 362

What To Test in the RDBMS ............................................................. 362

What To Test in the OS ......................................................................363

Summary.................................................................................................. 365

23 Miscellaneous Configurations ............................................................. 367

Financial Systems..................................................................................... 368

System Characteristics ......................................................................... 369

Design and Tuning Hints ................................................................... 369

Enhancements ......................................................................................... 372

Replicated Systems................................................................................... 374

System Characteristics ......................................................................... 374

Design and Tuning Hints ................................................................... 375

Distributed Systems ................................................................................. 377

System Characteristics ......................................................................... 378

Design and Tuning Hints ................................................................... 378

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Oracle Performance Tuning & Optimization

TextServer 3.0 Systems............................................................................. 379

System Characteristics ......................................................................... 379

Design and Tuning Hints ................................................................... 380

Enhancements ......................................................................................... 381

Oracle Office Systems .............................................................................. 382

System Characteristics ......................................................................... 383

Design and Tuning Hints ................................................................... 383

WebServer Systems .................................................................................. 386

System Characteristics ......................................................................... 386

Design and Tuning Hints ................................................................... 387

Enhancements ......................................................................................... 389

Summary.................................................................................................. 390

Part IV Tuning SQL 391

24 What Is a Well-Tuned SQL Statement?...............................................393

How To Identify Badly Formed SQL Statements .................................... 394

Transaction Processing ............................................................................. 395

SQL Statement Processing........................................................................397

Cursor Creation .................................................................................. 398

Statement Parsing ................................................................................ 399

Query Processing................................................................................. 400

Bind Variables ..................................................................................... 401

Statement Execution............................................................................ 401

Parallelization ...................................................................................... 401

Fetch Rows To Be Returned ............................................................... 401

Summary.................................................................................................. 402

25 Using EXPLAIN PLAN and SQL Trace .....................................................403

SQL Trace ............................................................................................... 404

SQL Trace Initialization ......................................................................404

Controlling SQL Trace ........................................................................405

SQL Trace Functionality .................................................................... 406

TKPROF Functionality .......................................................................407

Interpreting SQL Trace .......................................................................409

The EXPLAIN PLAN Command .................................................................. 414

EXPLAIN PLAN Initialization .................................................................. 414

Invoking EXPLAIN PLAN ........................................................................415

Extracting EXPLAIN PLAN Results .......................................................... 416

Registering Applications ........................................................................... 417

Summary.................................................................................................. 418

26 Tuning SQL Statements ...................................................................... 419

Tuning an Existing Application ............................................................... 420

Problem Analysis ................................................................................. 420

Tuning the Application .......................................................................422

xv

Contents

Designing a New Application .................................................................. 426

Indexes ................................................................................................ 426

Clusters ............................................................................................... 430

Hash Clusters ...................................................................................... 431

Packages, Procedures, and Functions ................................................... 432

Optimization Approaches ................................................................... 433

Discrete Transactions .......................................................................... 435

Summary.................................................................................................. 436

27 Using the Oracle Optimizer ................................................................ 437

How the Optimizer Works .......................................................................438

How To Specify an Optimization Mode ..................................................438

Optimization Methods............................................................................. 439

Rule-Based Approach .......................................................................... 440

Cost-Based Approach .......................................................................... 441

Using the ANALYZE Command .................................................................. 441

How To Run the ANALYZE Command ..................................................442

Data Dictionary Statistics ................................................................... 445

Hints ....................................................................................................... 447

Summary.................................................................................................. 447

28 Using Procedures, Functions, and Packages ....................................... 449

Review of the Library Cache .................................................................... 450

Procedures and Functions ........................................................................452

Procedures .......................................................................................... 453

Functions .............................................................................................453

How Procedures and Functions Operate ............................................. 454

How To Create Stored Procedures and Stored Functions.................... 456

How To Replace Procedures and Functions ........................................ 457

Packages ................................................................................................... 457

Summary.................................................................................................. 459

29 Providing for Data Integrity and Triggers ......................................... 461

Integrity Constraints ................................................................................ 462

Referential Integrity ............................................................................. 462

Integrity Constraints............................................................................ 465

Using Constraints................................................................................ 466

Triggers.................................................................................................... 469

Using Triggers..................................................................................... 469

Using Alerts ........................................................................................ 470

Creating Triggers ................................................................................ 470

Viewing Triggers ................................................................................. 471

Audit Trails ..............................................................................................472

Serial Reads ..............................................................................................473

Summary.................................................................................................. 473