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Fix bug lp:858148.

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Analysis:
The crash is a result of the same cause as all similar
bugs (lp:827416, lp:718763, lp:778413, lp:806943,
lp:611690). The general pattern is that some optimization
requires the evaluation of some condition (e.g. the WHERE
clause), and this condition contains a subquery, such that
the subquery itself requires a temporary table for its
execution. During the subquery execution the original
tables in the FROM clause are replaced by the temporary
table needed for the final GROUP or ORDER operation. All
this happens during optimization of the outer query. Later
when EXPLAIN is run for the subquery, explain attempts to
print the name of the tables in the FROM clause, but it
finds there a temporary table without a corresponding
TABLE_LIST object. The attempt to print the name of a
NULL table list results in a crash.

Solution:
This patch extends the fix to bug lp:702301, and dissalows
constant substitution of aggregate functions if the filter
condition used to check MIN/MAX keys is an expensive condition.
This commit is contained in:
unknown 2011-09-28 17:20:43 +03:00
parent 92dd45fd02
commit b53744b79e
3 changed files with 70 additions and 0 deletions
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34
mysql-test/r/subselect_innodb.result
View file

@ -271,4 +271,38 @@ FROM t2
WHERE (SELECT DISTINCT b FROM t3) > 0);
a
DROP TABLE t1, t2, t3;
#
# LP BUG#858148 Fourth crash in select_describe() with nested subqueries
#
CREATE TABLE t1 ( f1 int(11)) ENGINE=InnoDB;
CREATE TABLE t2 ( f1 int(11), f2 int(11), PRIMARY KEY (f1)) ;
CREATE TABLE t3 ( f3 int(11)) ENGINE=InnoDB;
EXPLAIN
SELECT MAX( f1 ) FROM t2
WHERE f2 >= (
SELECT SUM( f1 )
FROM t1
WHERE EXISTS (
SELECT f3
FROM t3
GROUP BY 1
)
);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
2 SUBQUERY t1 ALL NULL NULL NULL NULL 1
3 SUBQUERY t3 ALL NULL NULL NULL NULL 1 Using temporary; Using filesort
SELECT MAX( f1 ) FROM t2
WHERE f2 >= (
SELECT SUM( f1 )
FROM t1
WHERE EXISTS (
SELECT f3
FROM t3
GROUP BY 1
)
);
MAX( f1 )
NULL
drop table t1, t2, t3;
set optimizer_switch=@subselect_innodb_tmp;

34
mysql-test/t/subselect_innodb.test
View file

@ -264,4 +264,38 @@ WHERE t1.a = (
DROP TABLE t1, t2, t3;
--echo #
--echo # LP BUG#858148 Fourth crash in select_describe() with nested subqueries
--echo #
CREATE TABLE t1 ( f1 int(11)) ENGINE=InnoDB;
CREATE TABLE t2 ( f1 int(11), f2 int(11), PRIMARY KEY (f1)) ;
CREATE TABLE t3 ( f3 int(11)) ENGINE=InnoDB;
EXPLAIN
SELECT MAX( f1 ) FROM t2
WHERE f2 >= (
SELECT SUM( f1 )
FROM t1
WHERE EXISTS (
SELECT f3
FROM t3
GROUP BY 1
)
);
SELECT MAX( f1 ) FROM t2
WHERE f2 >= (
SELECT SUM( f1 )
FROM t1
WHERE EXISTS (
SELECT f3
FROM t3
GROUP BY 1
)
);
drop table t1, t2, t3;
set optimizer_switch=@subselect_innodb_tmp;

2
sql/opt_sum.cc
View file

@ -625,6 +625,8 @@ static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
/* Condition doesn't restrict the used table */
DBUG_RETURN(!cond->const_item());
}
else if (cond->is_expensive())
DBUG_RETURN(FALSE);
if (cond->type() == Item::COND_ITEM)
{
if (((Item_cond*) cond)->functype() == Item_func::COND_OR_FUNC)