Book Image

PostgreSQL Administration Cookbook, 9.5/9.6 Edition - Third Edition

Book Image

PostgreSQL Administration Cookbook, 9.5/9.6 Edition - Third Edition

Overview of this book

PostgreSQL is a powerful opensource database management system; now recognized as the expert's choice for a wide range of applications, it has an enviable reputation for performance and stability. PostgreSQL provides an integrated feature set comprising relational database features, object-relational, text search, Geographical Info Systems, analytical tools for big data and JSON/XML document management. Starting with short and simple recipes, you will soon dive into core features, such as configuration, server control, tables, and data. You will tackle a variety of problems a database administrator usually encounters, from creating tables to managing views, from improving performance to securing your database, and from using monitoring tools to using storage engines. Recipes based on important topics such as high availability, concurrency, replication, backup and recovery, as well as diagnostics and troubleshooting are also given special importance. By the end of this book, you will have all the knowledge you need to run, manage, and maintain PostgreSQL efficiently.
Table of Contents (13 chapters)

Finding unused indexes

Selecting the correct set of indexes for a workload is known to be a hard problem. It usually involves trial and error by developers and DBAs to get a good mix of indexes.

Tools for identifying slow queries exist, and many SELECT statements can be improved by the addition of an index.

What many people forget is to check whether the mix of indexes remains valuable over time, which is something for the DBA to investigate and optimize.

How to do it...

PostgreSQL keeps track of each access against an index. We can view that information and use it to see whether an index is unused, as follows:

postgres=# SELECT schemaname, relname, indexrelname, idx_scan FROM pg_stat_user_indexes ORDER BY idx_scan;
schemaname...