Slow SQL queries affect dashboards, reports, and application response times. Interviewers ask this question to see whether you can diagnose performance issues methodically instead of guessing.
Explain how you would optimize a SQL query that is running slowly in PostgreSQL. Your answer should cover:
Keep the answer practical and structured. The interviewer is not looking for deep PostgreSQL internals, but they do expect a clear workflow: inspect the execution plan, reduce unnecessary work, check indexes, and confirm improvements with measurement.