diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 34 |
1 files changed, 22 insertions, 12 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 151c22dc52c..76b1e182eb0 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -57,7 +57,8 @@ static bool update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse, uint tables, COND *conds, table_map table_map, SELECT_LEX *select_lex, st_sargable_param **sargables); -static bool sort_and_filter_keyuse(DYNAMIC_ARRAY *keyuse); +static bool sort_and_filter_keyuse(DYNAMIC_ARRAY *keyuse, + bool skip_unprefixed_keyparts); static int sort_keyuse(KEYUSE *a,KEYUSE *b); static bool create_ref_for_key(JOIN *join, JOIN_TAB *j, KEYUSE *org_keyuse, table_map used_tables); @@ -914,7 +915,6 @@ JOIN::optimize() "Impossible HAVING" : "Impossible WHERE"; tables= 0; error= 0; - choose_tableless_subquery_plan(); goto setup_subq_exit; } } @@ -966,7 +966,6 @@ JOIN::optimize() zero_result_cause= "No matching min/max row"; tables= 0; error=0; - choose_tableless_subquery_plan(); goto setup_subq_exit; } if (res > 1) @@ -1007,7 +1006,6 @@ JOIN::optimize() { DBUG_PRINT("info",("No tables")); error= 0; - choose_tableless_subquery_plan(); goto setup_subq_exit; } error= -1; // Error is sent to client @@ -1508,6 +1506,9 @@ JOIN::optimize() DBUG_RETURN(0); setup_subq_exit: + /* Choose an execution strategy for this JOIN. */ + if (!tables_list || !tables) + choose_tableless_subquery_plan(); /* Even with zero matching rows, subqueries in the HAVING clause may need to be evaluated if there are aggregate functions in the query. @@ -3036,7 +3037,16 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables_arg, COND *conds, if (update_ref_and_keys(join->thd, keyuse_array, stat, join->tables, conds, ~outer_join, join->select_lex, &sargables)) goto error; - if (keyuse_array->elements && sort_and_filter_keyuse(keyuse_array)) + /* + Keyparts without prefixes may be useful if this JOIN is a subquery, and + if the subquery may be executed via the IN-EXISTS strategy. + */ + bool skip_unprefixed_keyparts= + !(join->is_in_subquery() && + ((Item_in_subselect*)join->unit->item)->in_strategy & SUBS_IN_TO_EXISTS); + + if (keyuse_array->elements && + sort_and_filter_keyuse(keyuse_array, skip_unprefixed_keyparts)) goto error; DBUG_EXECUTE("opt", print_keyuse_array(keyuse_array);); } @@ -4505,7 +4515,8 @@ update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,JOIN_TAB *join_tab, Special treatment for ft-keys. */ -static bool sort_and_filter_keyuse(DYNAMIC_ARRAY *keyuse) +static bool sort_and_filter_keyuse(DYNAMIC_ARRAY *keyuse, + bool skip_unprefixed_keyparts) { KEYUSE key_end, *prev, *save_pos, *use; uint found_eq_constant, i; @@ -4532,12 +4543,12 @@ static bool sort_and_filter_keyuse(DYNAMIC_ARRAY *keyuse) { if (use->key == prev->key && use->table == prev->table) { - if (prev->keypart+1 < use->keypart || + if ((prev->keypart+1 < use->keypart && skip_unprefixed_keyparts) || (prev->keypart == use->keypart && found_eq_constant)) continue; /* remove */ } - else if (use->keypart != 0) // First found must be 0 - continue; + else if (use->keypart != 0 && skip_unprefixed_keyparts) + continue; /* remove - first found must be 0 */ } prev= use; @@ -16938,8 +16949,7 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order, select= tab->select; /* Currently ORDER BY ... LIMIT is not supported in subqueries. */ - DBUG_ASSERT(join->group_list || - !(join->unit->item && join->unit->item->is_in_predicate())); + DBUG_ASSERT(join->group_list || !join->is_in_subquery()); /* When there is SQL_BIG_RESULT do not sort using index for GROUP BY, @@ -20659,7 +20669,7 @@ JOIN::reoptimize(Item *added_where, table_map join_tables, /* added_keyuse contents is copied, and it is no longer needed. */ delete_dynamic(&added_keyuse); - if (sort_and_filter_keyuse(&keyuse)) + if (sort_and_filter_keyuse(&keyuse, true)) return REOPT_ERROR; optimize_keyuse(this, &keyuse); |