Priority: P0 (CRITICAL)
Slow query work starts with the query shape and evidence, not with random index creation.
Rules
- Capture the exact query, parameters, and access path.
- Run explain or equivalent plan inspection before adding indexes.
- Match indexes to filter, join, sort, and coverage needs.
- Fix N+1 at the query pattern or loading strategy, not by caching first.
Verify
- Explain plan was reviewed.
- Proposed index maps to a named query path.
- Write cost of the index is acceptable.
- Pagination or batch loading avoids deep scans or N+1 loops.
Anti-Patterns
- No blind indexes: every index needs a query owner.
- No cache-first latency fix: fix query shape before hiding it.
- No ORM opacity: inspect generated SQL when the ORM is involved.