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A Handy Postgres View for Optimization

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Learn about a Postgres view that can help optimize your database. We will also go over indexes and how they are used to find rows efficiently.

Table of Contents 📖

Postgres Indexes

A common way to optimize a Postgres database is to use indexes, data structures that improve the efficiency of data retrieval. They allow the database to quickly locate rows without scanning the entire table.

INFO: Think of how an index in a book is used to locate specific topics quicker. Postgres indexes help you find information faster.

Indexes are actually what are used to enfore uniqueness of a column or combination of columns. For example, the primary key below and unique email address will be enforced using an index.

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    email VARCHAR(255) UNIQUE
);

pg_stat_user_indexes View

Postgres provides several system views for monitoring and optimizing database performance, one of which is monitoring index usage. The view to do this is pg_stat_user_indexes.

SELECT schemaname, relname, indexrelname, idx_scan
FROM pg_stat_user_indexes;

Each row in the pg_stat_user_indexes view corresponds to an index in your database and provides statistical data related to its usage. By examining this view, you can gain insights into how your indexes are used. For example, the idx_scan column shows the number of index scans or queries that used this index. A high value indicates frequent usage while a zero suggests that the index may not be utilized. Checking this view for unused indexes is a good way to optimize your database. Unused indexes consume storage and slow down write operations. We could find unused indexes with the following command:

SELECT schemaname, relname, indexrelname, idx_scan
FROM pg_stat_user_indexes
WHERE idx_scan = 0;

WARNING: Just make sure you are not prematurely optimizing your database. This is just a quick way to find unused indexes.

A Handy Postgres View for Optimization