# Chapter 11. Indexes
Table of Contents
11.5. Combining Multiple Indexes
11.9. Index-Only Scans and Covering Indexes
11.10. Operator Classes and Operator Families
Indexes are a common way to enhance database performance. An index allows the database server to find and retrieve specific rows much faster than it could do without an index. But indexes also add overhead to the database system as a whole, so they should be used sensibly.