SQL EXPLAIN query plans: read what the database actually did

The query text is your request; the plan is the database's chosen route. Read the plan before changing indexes.

Short answer: run EXPLAIN to see intended operations and EXPLAIN ANALYZE in a safe environment to see actual timing and rows. Large estimate errors, broad scans, expensive sorts, and repeated nested-loop work are the useful clues.

EXPLAIN ANALYZE
SELECT * FROM orders WHERE account_id = 42 ORDER BY created_at DESC LIMIT 50;

EXPLAIN ANALYZE executes the query. Do not point it at a destructive statement on production merely to satisfy curiosity.

Measure, change one thing, and compare plans again.

Cover photo by Stanislav Kondratiev on Pexels.