Optimizer index caching in PostgreSQL

Optimizer index caching in PostgreSQL is the process by which the database caches the index pages in memory to speed up the execution of queries. This feature helps improve the performance of queries by reducing the number of disk I/O operations and accessing the data more quickly.

There are two ways to enable optimizer index caching in PostgreSQL:

  1. Using the shared_buffers configuration: This configuration is used to control the amount of memory that is used for caching data and index pages. By increasing the shared_buffers value, you can allocate more memory for index caching. This can be done by adding the following line to the postgresql.conf file:

2. Using the SET statement: You can also control the index caching at a session level using the SET statement. To enable index caching, you can use the following command:

This will enable the optimizer to use indexes instead of sequential scans, which can significantly improve query performance.

It’s important to note that optimizer index caching is a trade-off between performance and memory usage. If too much memory is allocated for index caching, other processes might be impacted, such as memory pressure and paging. To achieve the best performance, it’s recommended to adjust the shared_buffers configuration based on the system resources and the workload of the database.

About Shiv Iyer 157 Articles
Open Source Database Systems Engineer with a deep understanding of Optimizer Internals, Performance Engineering, Scalability and Data SRE. Shiv currently is the Founder, Investor, Board Member and CEO of multiple Database Systems Infrastructure Operations companies in the Transaction Processing Computing and ColumnStores ecosystem. He is also a frequent speaker in open source software conferences globally.