diff options
| author | Igor Babaev <igor@askmonty.org> | 2022-06-03 20:05:31 -0700 |
|---|---|---|
| committer | Igor Babaev <igor@askmonty.org> | 2022-06-03 20:05:31 -0700 |
| commit | d5d8695423ff9ed8fb245fe1dd1cf38d1c57856e (patch) | |
| tree | eeb040274853c1a1276361679a464772d62ab3bc /sql/opt_subselect.cc | |
| parent | 1f0333db90fb942b2a8435733184460ca3c56288 (diff) | |
| download | mariadb-git-bb-10.7-mdev-7487.tar.gz | |
MDEV-7487 Semi-join optimization for single-table UPDATE/DELETEsbb-10.7-mdev-7487
This is a preliminary patch.
Diffstat (limited to 'sql/opt_subselect.cc')
| -rw-r--r-- | sql/opt_subselect.cc | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc index 58d86876388..df8f8088811 100644 --- a/sql/opt_subselect.cc +++ b/sql/opt_subselect.cc @@ -675,9 +675,8 @@ int check_and_do_in_subquery_rewrites(JOIN *join) 3. Subquery does not have GROUP BY or ORDER BY 4. Subquery does not use aggregate functions or HAVING 5. Subquery predicate is at the AND-top-level of ON/WHERE clause - 6. We are not in a subquery of a single table UPDATE/DELETE that - doesn't have a JOIN (TODO: We should handle this at some - point by switching to multi-table UPDATE/DELETE) + 6. We are not in a top level subquery of a single table DELETE + with RETURNING 7. We're not in a table-less subquery like "SELECT 1" 8. No execution method was already chosen (by a prepared statement) 9. Parent select is not a table-less select @@ -692,9 +691,9 @@ int check_and_do_in_subquery_rewrites(JOIN *join) !select_lex->group_list.elements && !join->order && // 3 !join->having && !select_lex->with_sum_func && // 4 in_subs->emb_on_expr_nest && // 5 - select_lex->outer_select()->join && // 6 - (!thd->lex->m_sql_cmd || - thd->lex->m_sql_cmd->sql_command_code() == SQLCOM_UPDATE_MULTI) && + !(thd->lex->sql_command == SQLCOM_DELETE && // 6 + thd->lex->has_returning() && // 6 + !select_lex->outer_select()->outer_select()) && // 6 parent_unit->first_select()->leaf_tables.elements && // 7 !in_subs->has_strategy() && // 8 select_lex->outer_select()->table_list.first && // 9 @@ -7192,3 +7191,23 @@ bool TABLE_LIST::is_sjm_scan_table() { return is_active_sjm() && sj_mat_info->is_sj_scan; } + + +bool SELECT_LEX::is_sj_subselect_lifted_to_top() +{ + st_select_lex *sl= this; + st_select_lex *outer_sl= outer_select(); + for ( ; outer_sl; sl= outer_sl, outer_sl= outer_sl->outer_select()) + { + List_iterator_fast<Item_in_subselect> it(outer_sl->sj_subselects); + Item_in_subselect *in_subs; + while ((in_subs= it++)) + { + if (in_subs->unit->first_select() == sl) + break; + } + if (!in_subs) + return false; + } + return true; +} |