8.13. Internal Details of MySQL Optimizations

8.13.1. Range Optimization
8.13.2. Index Merge Optimization
8.13.3. Engine Condition Pushdown Optimization
8.13.4. Index Condition Pushdown Optimization
8.13.5. Use of Index Extensions
8.13.6. IS NULL Optimization
8.13.7. LEFT JOIN and RIGHT JOINOptimization
8.13.8. Nested-Loop Join Algorithms
8.13.9. Nested Join Optimization
8.13.10. Outer Join Simplification
8.13.11. Multi-Range Read Optimization
8.13.12. Block Nested-Loop and Batched Key Access Joins
8.13.13. ORDER BY Optimization
8.13.14. GROUP BY Optimization
8.13.15. DISTINCT Optimization
8.13.16. Subquery Optimization

This background information helps you to understand some of the terms you see in the EXPLAIN plan output. If you are rewriting queries to make them more efficient, or writing your own application logic for lookups, joining, or sorting, use this information to determine which optimizations you write yourself and which you can rely on MySQL to perform.

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