There was a time when it was rare for a company to have a data warehouse, but now it is an essential source of information to ensure that businesses make the right decisions. Initially, data warehouses could only be built and maintained by large corporations, but the recent advances in database software and computer hardware mean that now any organization can build a data warehouse or a data mart.
This book introduces the reader to the subject of data warehousing and data marts, with respect to implementing them using an Oracle 9i Release 2 (9iR2) database. It has been designed so that anyone new to this subject can gather a basic understanding of data warehousing and what is involved in designing, creating, implementing, and managing this solution using Oracle 9iR2.
We have endeavored to make the book easy to read and have provided lots of examples to illustrate how features are implemented. Each chapter focuses on a specific topic, and, by reading each chapter, you will learn the flow and all the basic steps required to build a data warehouse using Oracle 9iR2. The structure of the chapters is as follows:
Chapter 1 provides an introduction to the subject of data warehousing—introducing terms and discussing the need for a data warehouse or data mart.
Chapter 2 shows how to design a data warehouse and illustrates how to create dimensions and fact tables. At that time, the EASYDW shopping example is introduced; it is used for all of the examples in this book.
Chapter 3 describes various techniques that you can use to improve query performance in your data warehouse. Advice is given on how to make best use of features such as indexes and partitions.
Chapter 4 describes how you can achieve huge improvements in query response time by using materialized views and query rewrite.
Chapter 5 shows how to extract data, transform data, and then load this data into the data warehouse.
Chapter 6 looks at some of the Oracle tools you can use to build and report on your data warehouse. Specifically described are Oracle Warehouse Builder and Oracle Discoverer.
Chapter 7 discusses the techniques you can use to manage your data warehouse, such as backup and restore and managing partitions.
Chapter 8 describes how the Web can play a key role with your data warehouse and how it can be used to benefit your business.
Chapter 9 discusses the Oracle OLAP and Oracle data mining options, which are now part of the 9iR2 database and which can help you gain better insight into your business using the data warehouse.