16 11.3. Multicolumn Indexes
17 11.4. Indexes and ORDER BY
18 11.5. Combining Multiple Indexes
20 11.7. Indexes on Expressions
22 11.9. Index-Only Scans and Covering Indexes
23 11.10. Operator Classes and Operator Families
24 11.11. Indexes and Collations
25 11.12. Examining Index Usage
27 Indexes are a common way to enhance database performance. An index
28 allows the database server to find and retrieve specific rows much
29 faster than it could do without an index. But indexes also add overhead
30 to the database system as a whole, so they should be used sensibly.