database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-27 18:02:13 +03:00
Code Activity

MDEV-30538 Plans for SELECT and multi-table UPDATE/DELETE unexpectedly differ

Browse Source 
This patch allowed transformation of EXISTS subqueries into equivalent
IN predicands at the top level of WHERE conditions for multi-table UPDATE
and DELETE statements. There was no reason to prohibit the transformation
for such statements. The transformation provides more opportunities of
using semi-join optimizations.

Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2023-02-02 22:38:32 -08:00
parent 0845bce0d9
commit bef20b5f36
4 changed files with 201 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
mysql-test/main/update_use_source.result
View File

@ -76,7 +76,8 @@ rollback;
explain update t1 set c1=0 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 > 3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 8 Using where
2 DEPENDENT SUBQUERY a ALL NULL NULL NULL NULL 8 Using where
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
2 MATERIALIZED a ALL NULL NULL NULL NULL 8
start transaction;
update t1 set c1=c1+10 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 >= 3;
affected rows: 4
@ -317,7 +318,8 @@ rollback;
explain update t1 set c1=0 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 > 3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range t1_c2 t1_c2 5 NULL 2 Using where
2 DEPENDENT SUBQUERY a ref t1_c2 t1_c2 5 test.t1.c2 4 Using index
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
2 MATERIALIZED a range t1_c2 t1_c2 5 NULL 2 Using where; Using index
start transaction;
update t1 set c1=c1+10 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 >= 3;
affected rows: 4
@ -558,7 +560,8 @@ rollback;
explain update t1 set c1=0 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 > 3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range t1_c2 t1_c2 5 NULL 2 Using where
2 DEPENDENT SUBQUERY a ref t1_c2 t1_c2 5 test.t1.c2 1 Using index
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
2 MATERIALIZED a range t1_c2 t1_c2 5 NULL 2 Using where; Using index
start transaction;
update t1 set c1=c1+10 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 >= 3;
affected rows: 4
@ -800,7 +803,8 @@ rollback;
explain update t1 set c1=0 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 > 3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range t1_c2 t1_c2 5 NULL 2 Using where
2 DEPENDENT SUBQUERY a ref t1_c2 t1_c2 5 test.t1.c2 1 Using index
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
2 MATERIALIZED a range t1_c2 t1_c2 5 NULL 2 Using where; Using index
start transaction;
update t1 set c1=c1+10 where exists (select 'X' from t1 a where a.c2 = t1.c2) and c2 >= 3;
affected rows: 4