What methods exist for analyzing and optimizing SQL query execution?

Methods for analyzing and optimizing SQL queries include:

• EXPLAIN / EXPLAIN ANALYZE — shows the execution plan of a query, helps understand index usage, table scans, and costly operations.
• Query profiling — measuring execution time and resource consumption.
• Index optimization — creating or removing indexes to speed up data retrieval.
• Query rewriting — changing query structure for better performance (e.g., replacing subqueries with JOINs).
• Result caching — storing frequently used data to reduce load.

Example of using EXPLAIN in PostgreSQL:

EXPLAIN ANALYZE SELECT * FROM users WHERE age > 30;

This shows how the database plans to execute the query and how long it takes.