# Query Optimization

Turning SQL (or logical queries) into efficient execution plans.

## 🎯 Goals

- [ ] Read and reason about query plans
- [ ] Understand how indexes and statistics affect plans

## 📚 Checklist

- [ ] Learn what a **query planner/optimizer** does
- [ ] Use `EXPLAIN` / `EXPLAIN ANALYZE` in at least one RDBMS
- [ ] Understand **nested loop**, **hash**, and **merge joins** conceptually
- [ ] Recognize anti-patterns (SELECT \*, functions on indexed columns, etc.)

## 🔗 Related

- [[Indexes]]
- [[Query Planner]]
- [[02 - RDBMS]]