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MDEV-17360 Server crashes in optimize_keyuse

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This was a bug in the code of MDEV-12387 "Push conditions into materialized
subqueries". The bug manifested itself in rather rare situations. An
affected query must contain IN subquery predicate whose left operand
was an outer field of a mergeable derived table or view and right operand
was a materialized subquery.
The erroneous code in fact stripped off the Item_direct_ref wrapper from
the left operand of the IN subquery predicate when building equalities
produced by the conversion of the predicate into a semi-join. As a result
the left operand was not considered as an outer reference anymore and
used_tables() was calculated incorrectly. This caused a crash in the
function optimize_keyuse().
This commit is contained in:
Igor Babaev
2018-10-07 12:16:59 -07:00
parent 52f326cfb7
commit d03581bf3c
3 changed files with 33 additions and 3 deletions
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13
mysql-test/main/in_subq_cond_pushdown.result
View File

@@ -3855,3 +3855,16 @@ ORDER BY t4.d
a b c
x x NULL
DROP TABLE t1,t2,t3,t4;
#
# MDEV-17360: IN subquery predicate with outer reference in the left part
# that refers to a field of a mergeable derived table
#
CREATE TABLE t1 (id1 int) ENGINE=MYISAM;
INSERT INTO t1 VALUES (1814),(0),(NULL),(1);
CREATE TABLE t2 (id2 int) ENGINE=MYISAM;
SELECT 1 AS r FROM t2,t1,(SELECT * FROM t1) dt1
WHERE NOT EXISTS (SELECT id2 FROM t2
WHERE dt1.id1 IN (SELECT t2.id2 FROM t2
HAVING t2.id2 >= 1));
r
DROP TABLE t1,t2;

17
mysql-test/main/in_subq_cond_pushdown.test
View File

@@ -821,3 +821,20 @@ WHERE (t1.a) IN
);
DROP TABLE t1,t2,t3,t4;
--echo #
--echo # MDEV-17360: IN subquery predicate with outer reference in the left part
--echo # that refers to a field of a mergeable derived table
--echo #
CREATE TABLE t1 (id1 int) ENGINE=MYISAM;
INSERT INTO t1 VALUES (1814),(0),(NULL),(1);
CREATE TABLE t2 (id2 int) ENGINE=MYISAM;
SELECT 1 AS r FROM t2,t1,(SELECT * FROM t1) dt1
WHERE NOT EXISTS (SELECT id2 FROM t2
WHERE dt1.id1 IN (SELECT t2.id2 FROM t2
HAVING t2.id2 >= 1));
DROP TABLE t1,t2;

6
sql/opt_subselect.cc
View File

@@ -5512,7 +5512,7 @@ int select_value_catcher::send_data(List<Item> &items)
/**
@brief
Conjugate conditions after optimize_cond() call
Add new conditions after optimize_cond() call
@param thd the thread handle
@param cond the condition where to attach new conditions
@@ -5561,8 +5561,8 @@ Item *and_new_conditions_to_optimized_cond(THD *thd, Item *cond,
Item::Context(Item::ANY_SUBST,
((Item_func_equal *)item)->compare_type_handler(),
((Item_func_equal *)item)->compare_collation()),
((Item_func *)item)->arguments()[0]->real_item(),
((Item_func *)item)->arguments()[1]->real_item(),
((Item_func *)item)->arguments()[0],
((Item_func *)item)->arguments()[1],
&new_cond_equal))
li.remove();
}