Tài liệu ORACLE8i- P1 docx

Oracle Corporation currently “owns” the major share data-of the large database market, which is one sign data-of the superiority data-of Oracle’s product.The Oracle product is robust in

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ORACLE8i ™

Robert G Freeman Mark D Blomberg

MASTERING

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While this book was being written, the cowardly attacks on the World Trade Center, the Pentagon, and in Pennsylvania took place Thus, this book is dedicated to all those who died there and in other terrorist tragedies throughout the world This is dedicated to all the children who lost parents, the wives who lost husbands, and the husbands who lost wives It is dedicated to the grieving families and friends and to the hope of peace, but also to the hope of justice for those who feel that terror and destruction are reasonable

alternatives to peace and dialogue

As always, this work is dedicated to my family—my father and my mother, my brother and sisters, and most of all, my wife and children, who sacrifice their time with me in the

writing endeavors that I take on.

—Robert G Freeman

T here are numerous individuals who deserve recognition, and if we could put

them all on the front cover, we would Thanks to Richard Basile and ShagunTyagi, whose names do not appear on the front cover but who contributed

to the original content of this book

Thanks to my co-author Mark Blomberg, who really worked hard to make thishappen

Thanks, of course, to those who helped make this book what it is To my friend JeffKellum, who put me in contact with everyone else—including Richard Mills, our sup-portive associate publisher To the wonderful editing staff of this book, Leslie Light,Marilyn Smith, and Carol Henry Many thanks, as well, to technical editor AshokHanumanth In addition, thanks to Christine McGeever, acquisitions and develop-ment editor, who helped get the book off the ground The CD team and Dan Mum-mert did a fine job of assembling the CD material To the production staff, includingtalented compositor Adrian Woolhouse, thanks for making the book look great

Of course, there are countless people who helped and didn’t even know it Specialthanks to Steve Adams, Tim Stippler, Charles Pack, Mike Ault, Pete Sharman, John B.,

KG, and numerous other awesome people in the Oracle community!

Special thanks to the folks I work with: Nancy Von Dolteren, Yang Jiang, DonMongeon, Bob Just, Bill Barker, Wendy Hausler, John King, Bill Sullivan, GunjanNath, Richard McClain, Nirupam Majumdar, and Maritza Gonzalez You are all great!Thanks to those who provided moral support (and allowed me to not hold boards forboard breaking while I was writing this!): Mrs Skutnik, Mr Alfaro, and all those atMaster Clark’s Karate America in Jacksonville Thanks to our many friends, whoalways support us

Finally, thanks to my wife and my five kids, who came into my work area aboutonce a week just to refresh their memories of what I look like

Robert Freeman

I would like to take this opportunity to thank the staff at Sybex for all their hardwork through the long months of this project The staff at Sybex were helpful,resourceful, and most of all, knowledgeable.

I would also like to thank my wife and family for being tolerant of my absence andnot making the appropriate time to spend with them So thank you to my wife Ann,and daughters Rebecca and Dana

Finally, I would like to thank Robert Freeman for bringing me into this venture andgiving me the opportunity to realize one of my personal goals

To all involved, a truly grateful THANK YOU

Mark D Blomberg

W e want information… information ” Possibly you recognize these

words as the primary interest of a somewhat clandestine group, and astold by a character called Number 2 to Patrick McGoohan’s character

Number 6 (in the old TV show The Prisoner) Indeed, in this day,

infor-mation is king, and the speedy, accurate, and reliable retrieval of this inforinfor-mation isparamount

And if you wish to store and retrieve information quickly, Oracle’s flagship base product is the way to go Oracle Corporation currently “owns” the major share

data-of the large database market, which is one sign data-of the superiority data-of Oracle’s product.The Oracle product is robust in features and very fast—but it can also be complicatedand expensive to run As much as Oracle wishes to market its database product asbeing easy to manage and install, the truth is that an experienced DBA is generallyneeded for anything other than the most elemental installation and operation

We hear often from aspiring or beginning DBAs wondering how they can join theranks of Oracle DBAs Experience is undeniably one of the primary requirements forDBA excellence Yet, the need to acquire that experience also stands in the way of thejunior DBA’s advancement This experience requirement has made senior DBAs some-what scarce, and it’s also a principal reason for the good salaries offered to truly goodDBAs In other words, you can’t just pick up a book, go through the motions, andbecome a great DBA

The bottom line for employers is that it’s best to start out with the best and brightest.(“You can pay me now, or you can pay me later.”) If you’re investing millions in equip-ment and software, then you want to invest in talent, as well, at the beginning Onceyou have a stable, well-designed system up and running, then you can bring on thejuniors to maintain it

Getting one’s foot in the DBA door is difficult What you can do, however, islearn from each book you study Realize that just knowing the commands and howthe processes work is not enough to become a good DBA In addition, you need toknow about backup and recovery You need to know about tuning the database andtuning the SQL running in the database You need to know how to ferret statistics out

of the database and how to interpret them That’s what mastering Oracle database

INTRODUCTION

“

xxviii

This text goes beyond basic administration tasks, though it covers those as well.Within these pages you will find nuggets of our experience that might help you Wehope that you will also take away from this book the fact that administration of anOracle database is a multifaceted job Finally, remember that the best approach tomanagement of Oracle is a proactive one Don’t sit and wait for problems to occur

Is This Book for You?

We assume that the reader has fundamental knowledge of an Oracle database If you are

a beginning DBA with little or no understanding of Oracle, you should carefully readChapter 1 before going further In addition, we strongly suggest that you read a selec-tion of the following books; these are in order from basic to advanced skills coverage:

• Oracle DBA 101 by Marlene L Theriault, et al

• The Sybex Oracle Certified Professional (OCP) series of certification studyguides, including

• OCP: Oracle8i DBA SQL and PL/SQL Study Guide, 0-7821-2682-0

• Oracle8i Networking 101 by Marlene L Theriault

• Oracle8i Administration and Management by Michael R Ault

If you are a beginning DBA and do not have direct access to the Oracle product,you can download a copy of Oracle from Technet (www.technet.com), the Oracle web-site that contains demonstration copies of Oracle software Technet also containscode samples and Oracle documentation

Following are some other beneficial websites that you might use in your quest tomaster the Oracle database product:

www.revealnet.com This website provides information on the productofferings of RevealNet Labs (Quest Software), which develops state-of-the-art tech-nical knowledge bases and development/administration tools for Oracle, DB2,

and SQL Server The site also includes the Oracle DBA Pipelines, a forum forOracle database administrators to meet and share ideas and ask for help The syn-tax diagrams throughout this book and in Appendix E (on the CD) were producedusing the RevealNet Knowledge Base for Oracle Administration

www.oracle.com This is the main page of Oracle Corporation’s website

Here you can find information on Oracle and download certain products

education.oracle.com This is Oracle Corporation’s education site, whichoffers information on Oracle training courses and becoming an Oracle CertifiedProfessional

metalink.oracle.com Metalink is the online website for Oracle users Ifyou are an Oracle support customer, you will have access to this site Use it tosearch out help with existing Oracle bugs, to find Oracle documents, and toaccess Oracle forums on various subjects

www.ixora.com.au The Ixora site provides a great wealth of Unix-relatedOracle internal knowledge, as well as scripts that you can use to monitor thehealth of your database

What You Need to Know

As you pick up this book, understand that we have not devoted a great number of itspages to examining every fundamental detail of the Oracle database environment

You should already be comfortable with putting together SQL statements, and youshould know what SQL*Plus is

Although the book as a whole is not designed for beginners, beginning DBAs willfind Chapter 1 to be a quick primer that may well be enough to help them on the way

to mastering Oracle8i database administration

If you are a junior DBA, this book is right up your alley You’ll be comfortablealready with what’s involved in starting and stopping the database and working withsimple queries You’ll have some understanding of what the data dictionary is, andperhaps even be familiar with parts of it It’s our hope that you’ll eat this book up andthat it will give you the knowledge you need to become a truly great DBA

If you’re already a master DBA, we hope this text will be a trusted reference, andperhaps provide insight into some aspects of database administration that you want

to improve

INTRODUCTION

xxx

Conventions Used in This Book

One of the themes you’ll find in this book is consistency Within these pages we follow

a set of terminology standards that are in fairly common use in the Oracle community

We suggest that you adopt these standards in your daily operations, as well

Within the text, Oracle keywords are in uppercase (SELECT, INSERT, FROM, V$PARAMETER, PARTITION BY HASH) Table and column names are in uppercase,

as well, to distinguish them from the surrounding text (the EMP table; the EMP NOcolumn)

In addition, the following elements appear in this book:

NOTE Notes like this will appear from time to time Generally when we want add acomment that pertains to a particular section, we will do so in a note

TI P Tips like this are used to highlight particularly important procedures or processes

WARN I NG Warnings are used in the text to keep you from destroying somethinginadvertently When a warning appears, make sure you read it carefully We also use warn-ings to point out bugs in the Oracle8i product that we know about

How to Use This Book

You may find it easiest to read the chapters in order, but it’s not essential One of ourgoals was to make it possible for you to pick the text up and read any individual chap-ter without having to study several other chapters first We have grouped similarchapters logically, but otherwise (with a few exceptions) the chapters do not particu-larly “build” upon one another To make it easier for you to move among the chap-ters, we have included plenty of cross-references throughout the book

Of course, you’ll get the most benefit from this book by putting the material to realuse Take the examples and the generic routines we’ve provided and expand on them.Add and subtract from them and incorporate them into your own database manage-ment activities Experiment and enjoy!

What’s On the CD

The CD is chock full of goodies!

First, you’ll find a complete electronic edition of the book

All nine appendices, which are not in the printed book, are on the CD You’ll findthe Quick Reference appendices especially helpful They’re all in easy-to-search PDFformat

We’ve also provided some trial versions of products that can help you better age your database Note that these demos require that you purchase a license for con-tinued use; please read the provided supporting documentation and respect the rights

man-of the vendors who were kind enough to provide these files All man-of the following arefrom RevealNet Labs (Quest Software), www.revealnet.com:

• The Formatter Plus tool, which will do a quick syntax check of your SQL Itworks on code that has no Oracle syntax errors and is compilable or executable

on Oracle, but it is more permissive than the PL/SQL compiler or SQL*Plus environment

• The RevealNet Knowledge Base for Oracle Administration, to help you find tions for your questions about Oracle database administration

solu-• The Active PL/SQL Knowledge Base combines a comprehensive PL/SQL ence with an extensive PL/SQL Code Library It offers a valuable source of tech-nical expertise and a substantial library of procedures and functions

refer-Also included on the CD is the Oracle8i table, index, and SGA sizing spreadsheetdiscussed in Chapter 3 of the book, compliments of Mike Ault and TUSC

NOTE For late-breaking information about the CD, including additional files and ties, see README.TXT in the root directory of the CD

utili-INTRODUCTION

We have set up a website, www.masteringoracle.com, where you’ll find a link to e-mail Robert There are also some links to the book’s errata and other nifty things!

• Create an Oracle database

• Use the Oracle data dictionary

CHAPTER 1

Elements of Oracle Database Management

F E A T U R I N G : What is a DBA? 4 Introducing Oracle8i 5 Oracle internals 13 The physilogical Oracle 17 Fundamental Oracle principles 19 Environment settings 21 The Oracle SQL interface tools 22 Using Oracle SQL 29 Oracle PL/SQL 39

W elcome to Mastering Oracle8i We hope you find this book useful in

your DBA endeavors We’ve made every effort to fit as much pricelessinformation into this book as we could find, and hope you refer to

it daily

This book was written as a reference for the working Oracle DBA We assume most

of you already know Oracle well and want to explore Oracle8i in particular And ifyou’re new to Oracle, start right here The pace might seem fast and furious, butyou’ll manage quite well

Here in Chapter 1, we offer a broad view of Oracle and SQL fundamentals We’llbegin with a refresher on the DBA’s role Then we’ll review some database theory andOracle history Following that is a discussion of Oracle internals, the building blocksyou must master for successful database administration Next up is a discussion ofSQL*Plus and other elements of the Oracle database interface In addition, we willbriefly discuss the tools used to access the database, fundamental concepts of the SQLlanguage, and how to use SQL in the database All of these introductory subjects are,

of course, covered in depth in later chapters

What Is a DBA?

There seems to be an air of mystery surrounding database administrators and base management But really, being a DBA boils down to just a few basic qualities:

data-• Willingness to work long, sometimes hard hours

• Ability to ferret out the answers

• Determination to be the best

• The drive to succeed

• Knowledge of database administration

• Experience in database administrationNew DBAs can make up for a lack of the last two qualities by concentrating on thefirst four As you gain knowledge and experience, you’ll find that you don’t need towork so many long, hard hours quite as often as when you first started You’ll makefewer mistakes, and you’ll know where to look first for the answers—no ferrets required!

We aren’t trying to snowball you, though There will always be users who call you

at midnight, needing your help to recover a database But you’ll be up to the task.With knowledge and experience comes a better DBA who can truly become a “lazy

Robert’s Rants: Stick to Your Guns

As DBA, you’re very much the heart of the database If you fail, your database fails Donot be complacent with your database just because it’s performing well Do not ease

up on vigilance against risks to your systems, including policies and procedures that arenot in the best interest of your database Granted, there is a time to fight and a time tolay low, but this is your job The life of your database is your job

Yes, I’m on a soapbox; this is my chance to rant I’ve met many a DBA who rolled overand gave up because a project manager ordered them to do this or do that But don’t

forget that you are the DBA Go on out and look at the top job-hunting web sites, and

count the number of DBA jobs out there If you’re a DBA, you’re in high demand, soyou have the freedom to say no and stand by it I’ve had more than a few encounterswith a manager trying to bully me into doing something I just wasn’t going to do I’vesimply told them to go fly a kite I might even have mentioned something about myblack belt in karate, if they were particularly unpleasant

Of course, please do make sure you can back up your point of view with some goodsolid facts In the end, when you’re proven right, you and your database will be betterfor it, and so will the community using that database The point is, if you know you’recorrect, don’t back down for a second Compromise is fine, if it doesn’t compromise theintegrity of the database in your charge (or your own integrity) Someone may demandyour head, but it’s a sure bet that most of your company’s management knows thevalue of your position—and if they don’t, they will soon find out

Of course, if you end up getting fired, I didn’t say this and I’m not here

Introducing Oracle8i

In this section we will briefly discuss some relational database theory and some Oraclehistory We will take an overview of Oracle8i, the latest and greatest version of Oracle,and see how the Oracle database is both relational and object oriented

TIP Already an expert on relational theory? Already know that ACID means somethingelse besides what you used to melt things in chemistry class? You can skip this sectionaltogether; go ahead and move on to “Internals.”

INTRODUCING ORACLE8i

P A R T

I

CHAPTER 1 • ELEMENTS OF ORACLE DATABASE MANAGEMENT

6

Oracle is a relational database geared to meet the information processing ments of business Its features include support for all of the following:

require-• A large number of users and high-concurrency activity

• Read consistency among transactions, ensuring that other users will not seeyour changes until your changes are committed Neither will your changesaffect other users’ queries that started before your changes were committed

• A high degree of scalability

• Multiple recovery methods, including recovery to point of failure and recovery

to a specific point in time

• High availability using several methodologies, including standby database andreplication methodologies

Relational Theory—Briefly

In a paper presented in June 1970, “A Relational Model of Data for Large Shared DataBanks,” Dr E F Codd introduced the relational database model we still use today Ofcourse, Codd and others have added to this theory In particular, Dr Peter Chen, pro-fessor of computer science at Louisiana State University, originated the Entity Rela-tionship (ER) model He described it in a 1976 paper entitled “The Entity RelationshipModel - Toward a Unified View of Data.”

Within the relational database, data is generally stored in two-dimensional tables.Contained within the tables are sets of rows and columns A row represents a record

in the table, and one or more columns represent the details of that record.When

dis-cussing relational theory, the acronym ACID is used to represent the four

fundamen-tals of effective relational databases Oracle8i provides robust support for all theserelational fundamentals

A Atomicity Each transaction is a separate and distinct entity It happens in

whole or not at all

C Consistency Each database change is partitioned from other transactions.

Results from another transaction won’t mysteriously pop up in the middle ofanother transaction One transaction moves the database from one consistentstate to the next

I Isolation A transaction is not available to other users until it has been

commit-ted If you add a department and then add an employee to that department inthe same transaction, someone else cannot see the new department addeduntil you have committed the transaction, which takes place after you have

D Durability This fundamental implies that when a transaction is complete, its

presence in the database will be preserved and will not be lost Changes, oncecommitted, can be recovered

A relational database also demonstrates the principles of structures, operations,

and integrity that Codd defined Structures are tables, indexes, and views (for example).

They are manipulated with operations Operations are defined methods of allowing

the user access to the database and of manipulating that database Database

opera-tions adhere to integrity rules that govern the database Integrity rules define what

operations can be executed and when; all operations must follow these rules

Normalization

When you’re creating a database for an online transaction processing system (OLTP),there are generally two concerns: the speed and efficiency of transactions, and theoverall storage space required by the database One means of achieving the best

results is normalization—the process of organizing and refining database tables to

pro-vide accurate, unambiguous results when the tables are accessed For larger, data housing systems, the goals are generally the same, but the means to meet these goalstend to differ

ware-As a database is normalized, overall storage requirements are often reduced becausethere is less data redundancy Normalization can also, however, have a negativeimpact on performance (a statement that causes an argument in many camps) Thatsaid, the benefits of normalization usually outweigh any potential loss of perfor-mance In fact, normalization can improve performance because, overall, less data isprocessed

Typically, we start with a normalized database Often, however, the cost of forming the joins to retrieve data is higher than the additional disk space required tostore the data in a denormalized state Based on this and other performance factors,

per-we may choose to denormalize the database—tables and materialized views are ated to store data from various tables in denormalized format Although denormaliza-tion should not be the first line of response to query performance problems, it canyield good results In one case, we denormalized eight tables used in a recurring eight-table join and got runtimes down from several hours to just seconds Indeed, justabout any large data warehousing design comprises denormalized data stores

cre-Databases are typically described as being in third normal form (You can actually

normalize your database up to sixth normal form, but this is rarely done.) Here arethe steps of normalizing an object in a database:

First Normal Remove all repeating groups

Second Normal Link all entities to a primary key

Third Normal Link nonkey entities by keys, supported with foreign keys

INTRODUCING ORACLE8i

P A R T

I