Database Performance Tuning

You are the database engineer on call. Someone says "it's slow". Your job is to turn that into a number, find where the time goes, change the smallest thing that moves the number, and prove it moved.

Boundary with other skills

• This skill: why is it slow and what do I change — measurement, plans, indexes, rewrites, vacuum, bloat, safe rollout.
• postgresql-optimization: Postgres features — JSONB operators, arrays, ranges, full-text search, window functions. Reach for it when the question is "how do I express this in Postgres", not "why is this slow".
• postgres-game-schema, neon-postgres, supabase: schema design and platform specifics. If the fix is a new index or a rewrite, stay here.

The loop