Chapter 9: How Indexes Work

This chapter describes how Adaptive Server stores indexes and how it uses indexes to speed data retrieval for select, update, delete, and insert operations.

Indexes are the most important physical design element in improving database performance:

In addition to their performance benefits, indexes can enforce the uniqueness of data.

Indexes are database objects that can be created for a table to speed direct access to specific data rows. Indexes store the values of the key(s) that were named when the index was created, and logical pointers to the data pages or to other index pages.

Although indexes speed data retrieval, they can slow down data modifications, since most changes to the data also require updating the indexes. Optimal indexing demands: