The document summarizes the query path in MySQL 8.0, including 4 main stages: parsing, resolving, optimizing, and executing. It describes the main components and related code for each stage. For example, the parser converts SQL to an AST using sql_parse.cc. The resolver performs semantic checking and subquery optimizations. The optimizer chooses the most efficient execution plan using statistics and cost modeling. Finally, the executor runs the plan using techniques like nested loops joins, row iterators, and index condition pushdowns. It notes some features not covered like privileges, partitioning, and distribution related optimizations.

1. MySQL 8.0 Server Query Path
2019-10-01 - 宸风

2. Arch

3. 目录
1 MySQL Parser
2 MySQL Resolver (rewriter)
3 MySQL Optimizer
4 MySQL Executor

4. MySQL Parser

5. Parser - AST

6. Parser - AST
Related codes:
- sql_parse.cc
- sql_yacc.cc
- item*.h/.cc
Ref: http://mysql.taobao.org/monthly/2017/04/02/

7. Parser - Item
Ref: MySQL Item 源码阅读笔记
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8. MySQL Resolver

9. Resolver

10. Resolver – Semantic check

11. Resolver - View Merge or Materialization

12. Resolver - View Merge Example
https://dev.mysql.com/doc/refman/8.0/en/view-algorithms.html

13. Resolver – Subquery Optimization
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14. Resolver – Subquery Optimization
https://mariadb.com/kb/en/library/non-semi-join-subquery-optimizations/#the-in-to-exists-transformation

15. Resolver – Subquery Optimization Rewrite Algos

16. Resolver – Subquery Optimization Rewrite Algos

17. Subquery Optimization SemiJoin Execution Algos

18. Subquery Optimization SemiJoin Execution Algos

19. Subquery Optimization SemiJoin Execution Algos

20. Subquery Optimization SemiJoin Execution Algos

21. Subquery Optimization SemiJoin Execution Algos

22. MySQL Optimizer

23. SQL Optimizer – Main procedure
Ref: MySQL 8.0 Optimizer 源码笔记
Ref: MySQL 8.0 Distinct 源码笔记

24. SQL Optimizer

25. SQL Optimizer

26. SQL Optimizer - statistics

27. SQL Optimizer – cost model

28. SQL Optimizer – join reorder

29. SQL Optimizer – access method
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30. SQL Optimizer – access method

31. MySQL Executor

32. SQL Executor – do select

33. SQL Executor – Nested-Loop Join
HashJoin is coming in MySQL 8.0.17

34. SQL Executor – RowIterator

35. SQL Executor – MRR, BKA

36. SQL Executor – ICP (Index cond pushdown)

37. Missing branches/features in QueryPath
- privilege
- fulltext
- CTE
- table function
- partitioned table
- window
- GIS/JSON, etc.
- perf & track
- agg & distinct
- rollup
- distribution related
- etc …