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MDEV-22498: SIGSEGV in Bitmap<64u>::merge on SELECT

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For the case when the optimizer does the IN-EXISTS transformation,
the equality condition is injected in the WHERE OR HAVING clause of
the subquery. If the select list of the subquery has a reference to
the parent select make sure to use the reference and not the original
item.
This commit is contained in:
Varun Gupta 2020-05-11 19:56:14 +05:30
parent ee5152fc4b
commit efd68f5e31
3 changed files with 62 additions and 3 deletions
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32
mysql-test/r/subselect4.result
View file

@ -2534,3 +2534,35 @@ x
c1
1
drop table t1;
#
# MDEV-22498: SIGSEGV in Bitmap<64u>::merge on SELECT
#
set @save_sql_select_limit= @@sql_select_limit;
SET sql_select_limit=0;
CREATE TABLE t1(b INT, c INT);
CREATE TABLE t2(a INT, b INT);
INSERT INTO t1 VALUES (1,1),(2,2),(3,3);
INSERT INTO t2 VALUES (1,1),(2,2),(3,3);
EXPLAIN EXTENDED SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL NULL Zero limit
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 3 100.00
Warnings:
Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1
Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1
Note 1003 select sum(`test`.`t2`.`a`) AS `sum(a)`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` having <in_optimizer>(`test`.`t2`.`a`,<exists>(select `test`.`t2`.`b` from `test`.`t1` where (<cache>(`test`.`t2`.`a`) = `test`.`t2`.`b`)))
SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
sum(a) a b
SET @@sql_select_limit= @save_sql_select_limit;
EXPLAIN EXTENDED SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 3 100.00
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 3 100.00
Warnings:
Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1
Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1
Note 1003 select sum(`test`.`t2`.`a`) AS `sum(a)`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` having <expr_cache><`test`.`t2`.`a`,`test`.`t2`.`b`>(<in_optimizer>(`test`.`t2`.`a`,<exists>(select `test`.`t2`.`b` from `test`.`t1` where (<cache>(`test`.`t2`.`a`) = `test`.`t2`.`b`))))
SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
sum(a) a b
6 1 1
DROP TABLE t1,t2;

24
mysql-test/t/subselect4.test
View file

@ -2075,3 +2075,27 @@ insert into t1 values(2,1),(1,2);
select (select c1 from t1 group by c1,c2 order by c1 limit 1) as x;
(select c1 from t1 group by c1,c2 order by c1 limit 1);
drop table t1;
--echo #
--echo # MDEV-22498: SIGSEGV in Bitmap<64u>::merge on SELECT
--echo #
set @save_sql_select_limit= @@sql_select_limit;
SET sql_select_limit=0;
CREATE TABLE t1(b INT, c INT);
CREATE TABLE t2(a INT, b INT);
INSERT INTO t1 VALUES (1,1),(2,2),(3,3);
INSERT INTO t2 VALUES (1,1),(2,2),(3,3);
let $query=
SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
eval EXPLAIN EXTENDED $query;
eval $query;
SET @@sql_select_limit= @save_sql_select_limit;
eval EXPLAIN EXTENDED $query;
eval $query;
DROP TABLE t1,t2;

9
sql/item_subselect.cc
View file

@ -2135,10 +2135,13 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN *join,
}
else
{
/*
No need to use real_item for the item, as the ref items that are possible
in the subquery either belong to views or to the parent select.
For such case we need to refer to the reference and not to the original
item.
*/
Item *item= (Item*) select_lex->item_list.head();
if (item->type() != REF_ITEM ||
((Item_ref*)item)->ref_type() != Item_ref::VIEW_REF)
item= item->real_item();
if (select_lex->table_list.elements)
{