Databases & System Design•Part 2: Relational Databases (RDBMS / PostgreSQL / MySQL) (6 - 25)
EXPLAIN vs EXPLAIN ANALYZE:
In Simple Words:
EXPLAIN: Shows the optimizer's estimated execution plan without running the query.EXPLAIN ANALYZE: Actually executes the query, reporting real execution times, buffer hits, and scan types (Sequential Scan vs Index Scan).
sql
EXPLAIN (ANALYZE, BUFFERS)
SELECT u.name, count(o.id)
FROM users u
JOIN orders o ON u.id = o.user_id
WHERE u.created_at >= '2025-01-01'
GROUP BY u.name;