PostgreSQL ORDER BY Performance Optimization

Why ORDER BY Slows Queries

Sorting large datasets requires memory and may cause disk-based sorting if work_mem is insufficient.

Use Index for Sorting

Create an index matching the ORDER BY column.

CREATE INDEX idx_users_created_at
ON users(created_at);

Combine ORDER BY and LIMIT

Using LIMIT reduces sorting overhead significantly.

Increase work_mem Carefully

SET work_mem = '64MB';