MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields

Fix by Sergey Petrunia.

This patch only prevents the evaluation of expensive subqueries during optimization.
The crash reported in this bug has been fixed by some other patch.
The fix is to call value->is_null() only when  !value->is_expensive(), because is_null()
may trigger evaluation of the Item, which in turn triggers subquery evaluation if the
Item is a subquery.
This commit is contained in:
unknown 2012-10-12 16:44:54 +03:00
parent fc941f8a21
commit e47cdfdfb6
7 changed files with 133 additions and 3 deletions

View File

@ -6847,6 +6847,27 @@ id select_type table type possible_keys key key_len ref rows Extra
2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index
DROP TABLE t1,t2;
#
# MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
#
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index a a 5 NULL 2 Using where; Using index
2 SUBQUERY <subquery3> ALL distinct_key NULL NULL NULL 1
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
3 MATERIALIZED t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
a
drop table t1, t2, t3;
#
# MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
#
CREATE TABLE t1 (a INT, KEY(a));

View File

@ -6845,6 +6845,26 @@ id select_type table type possible_keys key key_len ref rows Extra
2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index
DROP TABLE t1,t2;
#
# MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
#
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index a a 5 NULL 2 Using where; Using index
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
a
drop table t1, t2, t3;
#
# MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
#
CREATE TABLE t1 (a INT, KEY(a));

View File

@ -6842,6 +6842,27 @@ id select_type table type possible_keys key key_len ref rows Extra
2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index
DROP TABLE t1,t2;
#
# MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
#
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index a a 5 NULL 2 Using where; Using index
2 SUBQUERY <subquery3> ALL distinct_key NULL NULL NULL 1
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
3 MATERIALIZED t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
a
drop table t1, t2, t3;
#
# MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
#
CREATE TABLE t1 (a INT, KEY(a));

View File

@ -6853,6 +6853,27 @@ id select_type table type possible_keys key key_len ref rows Extra
2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index
DROP TABLE t1,t2;
#
# MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
#
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index a a 5 NULL 2 Using where; Using index
2 SUBQUERY <subquery3> ALL distinct_key NULL NULL NULL 1
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
3 MATERIALIZED t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
a
drop table t1, t2, t3;
#
# MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
#
CREATE TABLE t1 (a INT, KEY(a));

View File

@ -6842,6 +6842,27 @@ id select_type table type possible_keys key key_len ref rows Extra
2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index
DROP TABLE t1,t2;
#
# MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
#
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index a a 5 NULL 2 Using where; Using index
2 SUBQUERY <subquery3> ALL distinct_key NULL NULL NULL 1
2 SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
3 MATERIALIZED t3 ALL NULL NULL NULL NULL 2
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
a
drop table t1, t2, t3;
#
# MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
#
CREATE TABLE t1 (a INT, KEY(a));

View File

@ -5756,6 +5756,29 @@ EXPLAIN SELECT * FROM t1 WHERE EXISTS ( SELECT a FROM t1, t2 WHERE b = a GROUP B
DROP TABLE t1,t2;
--echo #
--echo # MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields
--echo #
CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM;
INSERT INTO t1 VALUES (8),(0);
CREATE TABLE t2 (b INT, c VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES (4,'j'),(6,'v');
CREATE TABLE t3 (d VARCHAR(1)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('b'),('c');
EXPLAIN
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
SELECT * FROM t1
WHERE a = (SELECT MAX(b) FROM t2 WHERE c IN (SELECT MAX(d) FROM t3)) OR a = 10;
drop table t1, t2, t3;
--echo #
--echo # MDEV-405: Server crashes in test_if_skip_sort_order on EXPLAIN with GROUP BY and HAVING in EXISTS subquery
--echo #

View File

@ -3876,8 +3876,10 @@ merge_key_fields(KEY_FIELD *start,KEY_FIELD *new_fields,KEY_FIELD *end,
new_fields->null_rejecting);
}
else if (old->eq_func && new_fields->eq_func &&
((old->val->const_item() && old->val->is_null()) ||
new_fields->val->is_null()))
((old->val->const_item() && !old->val->is_expensive() &&
old->val->is_null()) ||
(!new_fields->val->is_expensive() &&
new_fields->val->is_null())))
{
/* field = expression OR field IS NULL */
old->level= and_level;
@ -3891,7 +3893,8 @@ merge_key_fields(KEY_FIELD *start,KEY_FIELD *new_fields,KEY_FIELD *end,
Remember the NOT NULL value unless the value does not depend
on other tables.
*/
if (!old->val->used_tables() && old->val->is_null())
if (!old->val->used_tables() && !old->val->is_expensive() &&
old->val->is_null())
old->val= new_fields->val;
}
else