Book Image

PostgreSQL High Performance Cookbook

By : Chitij Chauhan, Dinesh Kumar
Book Image

PostgreSQL High Performance Cookbook

By: Chitij Chauhan, Dinesh Kumar

Overview of this book

PostgreSQL is one of the most powerful and easy to use database management systems. It has strong support from the community and is being actively developed with a new release every year. PostgreSQL supports the most advanced features included in SQL standards. It also provides NoSQL capabilities and very rich data types and extensions. All of this makes PostgreSQL a very attractive solution in software systems. If you run a database, you want it to perform well and you want to be able to secure it. As the world’s most advanced open source database, PostgreSQL has unique built-in ways to achieve these goals. This book will show you a multitude of ways to enhance your database’s performance and give you insights into measuring and optimizing a PostgreSQL database to achieve better performance. This book is your one-stop guide to elevate your PostgreSQL knowledge to the next level. First, you’ll get familiarized with essential developer/administrator concepts such as load balancing, connection pooling, and distributing connections to multiple nodes. Next, you will explore memory optimization techniques before exploring the security controls offered by PostgreSQL. Then, you will move on to the essential database/server monitoring and replication strategies with PostgreSQL. Finally, you will learn about query processing algorithms.
Table of Contents (19 chapters)
PostgreSQL High Performance Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Finding unused indexes


In this recipe, we will be discussing how to find the unused indexes from their creation time, which is utilizing the unnecessary I/O.

Getting ready

In a database, unused indexes will cause an unnecessary I/O for each write operation to be written into a table. To find these unused indexes, we have to depend on the number of scans that an index has performed as of that moment. From the time of index creation, if the index scan count is zero and the index is not a primary key index, then we can treat that as an unused index.

Note

To get the number of index scans of a table, we have to depend on PostgreSQL statistical counters. However, these counters can be reset to zero using pg_stat_reset(). It would be wise to check when was the last time the stats were reset, using the stats_reset column from the pg_stat_database view.

How to do it...

Let's run the following query to get the list of unused indexes from the database:

        benchmarksql=# SELECT 
        indrelid::regclass...