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MDEV-34870: implement join order hints

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This commit implements optimizer hints allowing to affect the order
of joining tables:

 - JOIN_FIXED_ORDER similar to existing STRAIGHT_JOIN hint;
 - JOIN_ORDER to apply the specified table order;
 - JOIN_PREFIX to hint what tables should be first in the join;
 - JOIN_SUFFIX to hint what tables should be last in the join.
This commit is contained in:
Oleg Smirnov
2025-01-30 20:56:36 +07:00
parent c4fe794d22
commit 349f5bf2da
18 changed files with 4198 additions and 1311 deletions
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9
sql/sql_select.h
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@@ -378,8 +378,9 @@ typedef struct st_join_table {
*/
table_map dependent;
/*
key_dependent is dependent but add those tables that are used to compare
with a key field in a simple expression. See add_key_field().
Normally `key_dependent` is the same as `dependent` but may also include
tables that are used to compare with a key field in a simple expression
(see add_key_field()).
It is only used to prune searches in best_extension_by_limited_search()
*/
table_map key_dependent;
@@ -1955,6 +1956,10 @@ public:
bool optimize_upper_rownum_func();
void calc_allowed_top_level_tables(SELECT_LEX *lex);
table_map get_allowed_nj_tables(uint idx);
bool propagate_dependencies(JOIN_TAB *stat);
void update_key_dependencies();
table_map *export_table_dependencies() const;
void restore_table_dependencies(table_map *orig_dep_array);
private:
/**