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

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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
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70
mysql-test/main/multi_update.test
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@ -1130,3 +1130,73 @@ EXPLAIN FORMAT=JSON UPDATE t2 JOIN t1 USING(a) SET t2.part=2 WHERE t2.part=1 AND
EXPLAIN FORMAT=JSON UPDATE t2 JOIN t1 USING(a) SET t2.part=3 WHERE t2.part=2 AND t1.part=2;
DROP TABLES t1, t2;
--echo # End of 10.3 tests
--echo #
--echo # MDEV-28538: multi-table UPDATE/DELETE with possible exists-to-in
--echo #
create table t1 (c1 int, c2 int, c3 int, index idx(c2));
insert into t1 values
(1,1,1),(3,2,2),(1,3,3),
(2,1,4),(2,2,5),(4,3,6),
(2,4,7),(2,5,8);
create table t2 (c1 int, c2 int, c3 int, index idx(c2));
insert into t2 values
(1,7,1),(1,8,2),(1,3,3),
(2,1,4),(2,2,5),(2,3,6),
(2,4,7),(2,5,8);
create table t3 (c1 int, c2 int, c3 int, index idx(c2));
insert into t3 values
(1,1,1),(1,2,2),(1,3,3),
(2,1,4),(2,2,5),(2,3,6),
(2,4,7),(2,5,8);
insert into t3 select c1+1, c2+2, c3 from t3;
insert into t3 select c1, c2+2, c3 from t3;
analyze table t1,t2,t3 persistent for all;
let $c=
t1.c2 = t3.c2 and
t1.c1 > 1 and
exists (select 'X' from t2 where t2.c1 = t1.c1 and t2.c2 > 4);
let $q1=
select * from t1,t3
where $c;
eval explain $q1;
let $q2=
delete from t1 using t1,t3
where $c;
eval explain $q2;
let $q3=
update t1,t3 set t1.c1 = t1.c1+10
where $c;
eval explain $q3;
create table t as select * from t1;
eval $q1;
select * from t1;
eval $q2;
select * from t1;
truncate table t1;
insert into t1 select * from t;
analyze table t1 persistent for all;
eval $q3;
select * from t1;
drop table t1,t2,t3,t;
--echo # End of 10.4 tests