Chapter 11. Indexes

Table of Contents

11.1. Introduction
11.2. Index Types
11.3. Multicolumn Indexes
11.4. Indexes and ORDER BY
11.5. Combining Multiple Indexes
11.6. Unique Indexes
11.7. Indexes on Expressions
11.8. Partial Indexes
11.9. Operator Classes and Operator Families
11.10. Indexes and Collations
11.11. Index-Only Scans
11.12. Examining Index Usage

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.

Each index is maintained locally in Coordinator and Datanode in Postgres-XL. Cross validation of index entries among Coordinators and Datanodes is not performed in the current implementation.