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Introduction

The inspiration for the material contained in this book comes from my experiences developing Oracle software and from working with fellow Oracle developers and DBAs to help them build reliable and robust applications based on the Oracle database. The book is basically a reflection of what I do every day and of the issues I see people encountering each and every day.

I covered what I felt was most relevant, namely, the Oracle database and its architecture. I could have written a similarly titled book explaining how to develop an application using a specific language and architecture — for example, one using JavaServer Pages that speaks to Enterprise JavaBeans, which in turn uses JDBC to communicate with Oracle. However, at the end of the day, you really do need to understand the topics covered in this book in order to build such an application successfully. This book deals with what I believe needs to be universally known to develop successfully with Oracle, whether you are a Visual Basic programmer using ODBC, a Java programmer using EJBs and JDBC, or a Perl programmer using DBI Perl. This book does not promote any specific application architecture; it does not compare three-tier to client/server. Rather, it covers what the database can do and what you must understand about the way it works. Since the database is at the heart of any application architecture, the book should have a broad audience.

As the title suggests, Expert Oracle Database Architecture concentrates on the database architecture and how the database itself works. I cover the Oracle database architecture in depth: the files, memory structures, and processes that comprise an Oracle database and instance. I then move on to discuss important database topics such as locking, concurrency controls, how transactions work, and redo and undo, and why it is important for you to know about these things. Lastly, I examine the physical structures in the database such as tables, indexes, and datatypes, covering techniques for making optimal use of them.

What This Book Is About

One of the problems with having plenty of development options is that it’s sometimes hard to figure out which one might be the best choice for your particular needs. Everyone wants as much flexibility as possible (as many choices as they can possibly have), but they also want things to be very cut and dried—in other words, easy. Oracle presents developers with almost unlimited choice. No one ever says, “You can’t do that in Oracle.” Rather, they say, “How many different ways would you like to do that in Oracle?” I hope that this book will help you make the correct choice.

This book is aimed at those people who appreciate the choice but would also like some guidelines and practical implementation details on Oracle features and functions. For example, Oracle has a really neat feature called parallel execution. The Oracle documentation tells you how to use this feature and what it does. Oracle documentation does not, however, tell you when you should use this feature and, perhaps even more important, when you should not use this feature. It doesn’t always tell you the implementation details of this feature, and if you’re not aware of them, this can come back to haunt you (I’m not referring to bugs, but the way the feature is supposed to work and what it was really designed to do).

In this book, I strove to not only describe how things work but also explain when and why you would consider using a particular feature or implementation. I feel it is important to understand not only the “how” behind things but also the “when” and “why” as well as the “when not” and “why not!”

Who Should Read This Book

The target audience for this book is anyone who develops applications with Oracle as the database back end. It is a book for professional Oracle developers who need to know how to get things done in the database. The practical nature of the book means that many sections should also be very interesting to the DBA. Most of the examples in the book use SQL*Plus to demonstrate the key features, so you won’t find out how to develop a really cool GUI — but you will find out how the Oracle database works, what its key features can do, and when they should (and should not) be used.

This book is for anyone who wants to get more out of Oracle with less work. It is for anyone who wants to see new ways to use existing features. It is for anyone who wants to see how these features can be applied in the real world (not just examples of how to use the feature, but why the feature is relevant in the first place). Another category of people who would find this book of interest is technical managers in charge of the developers who work on Oracle projects. In some respects, it is just as important that they understand why knowing the database is crucial to success. This book can provide ammunition for managers who would like to get their personnel trained in the correct technologies or ensure that personnel already know what they need to know.

To get the most out of this book, the reader should have Knowledge of SQL: You don’t have to be the best SQL coder ever, but a good working knowledge will help.

An understanding of PL/SQL: This isn’t a prerequisite, but it will help you to absorb the examples. This book will not, for example, teach you how to program a FOR loop or declare a record type; the Oracle documentation and numerous books cover this well. However, that’s not to say that you won’t learn a lot about PL/SQL by reading this book. You will. You’ll become very intimate with many features of PL/SQL, you’ll see new ways to do things, and you’ll become aware of packages/features that perhaps you didn’t know existed.

Exposure to some third-generation language (3GL), such as C or Java: I believe that anyone who can read and write code in a 3GL language will be able to successfully read and understand the examples in this book.

Familiarity with the Oracle Database Concepts manual.