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Oracle SQL by Carol McCullough-Dieter, Gavin JT Powell

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21

Indexes and Clusters

In this chapter:

  • What is an index and what is the purpose of an index?

  • What types of indexes are there, and how do they work?

  • What are the special attributes of indexes?

  • What is a cluster?

Recent chapters have discussed various database objects such as tables, views, and constraints. This fourth chapter on database objects covers indexing and clustering. Understanding database objects is essential to a proper understanding of Oracle SQL, particularly with respect to building efficient SQL code; tuning is another subject.1 It is important to understand different database objects, indexes and clusters included.

21.1 Indexes

Let’s start by briefly discussing what exactly an index is, followed by some salient facts about ...

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