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Test case for bug lp:1001117, MySQL BUG#12330344

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Analysis:
The problem in the original MySQL bug is that the range optimizer
performs its analysis in a separate MEM_ROOT object that is freed
after the range optimzier is done. During range analysis get_mm_tree
calls Item_func_like::select_optimize, which in turn evaluates its
right argument. In the test case the right argument is a subquery.

In MySQL, subqueries are optimized lazyly, thus the call to val_str
triggers optimization for the subquery. All objects needed by the
subquery plan end up in the temporary MEM_ROOT used by the range
optimizer. When execution ends, the JOIN::cleanup process tries to
cleanup objects of the subquery plan, but all these objects are gone
with the temporary MEM_ROOT. The solution for MySQL is to switch the
mem_root.

In MariaDB with the patch for bug lp:944706, all constant subqueries
that may be used by the optimization process are preoptimized. Therefore
Item_func_like::select_optimize only triggers subquery execution, and
the above problem is not present.

The patch however adds a test whether the evaluated right argument of
the LIKE predicate is expensive. This is consistent with our approach
not to evaluate expensive expressions during optimization.
This commit is contained in:
unknown 2012-05-24 14:08:28 +03:00
parent e5bca74bfb
commit 4fa89b5fe0
3 changed files with 26 additions and 1 deletions
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12
mysql-test/r/partition.result
View file

@ -2461,3 +2461,15 @@ SELECT 1 FROM t1 JOIN t1 AS t2 USING (a);
1
1
drop table t1;
#
# LP BUG#1001117 Crash on a simple select that uses a temptable view
# MySQL Bug #12330344 Crash and/or valgrind errors in free_io_cache with join, view,
# partitioned table
#
CREATE TABLE t1(a INT PRIMARY KEY) PARTITION BY LINEAR KEY (a);
CREATE ALGORITHM=TEMPTABLE VIEW vtmp AS
SELECT 1 FROM t1 AS t1_0 JOIN t1 ON t1_0.a LIKE (SELECT 1 FROM t1);
SELECT * FROM vtmp;
1
DROP VIEW vtmp;
DROP TABLE t1;

13
mysql-test/t/partition.test
View file

@ -2463,3 +2463,16 @@ INSERT INTO t1 VALUES (6,8,10);
SELECT 1 FROM t1 JOIN t1 AS t2 USING (a);
drop table t1;
--echo #
--echo # LP BUG#1001117 Crash on a simple select that uses a temptable view
--echo # MySQL Bug #12330344 Crash and/or valgrind errors in free_io_cache with join, view,
--echo # partitioned table
--echo #
CREATE TABLE t1(a INT PRIMARY KEY) PARTITION BY LINEAR KEY (a);
CREATE ALGORITHM=TEMPTABLE VIEW vtmp AS
SELECT 1 FROM t1 AS t1_0 JOIN t1 ON t1_0.a LIKE (SELECT 1 FROM t1);
SELECT * FROM vtmp;
DROP VIEW vtmp;
DROP TABLE t1;

2
sql/item_cmpfunc.cc
View file

@ -4736,7 +4736,7 @@ longlong Item_func_like::val_int()
Item_func::optimize_type Item_func_like::select_optimize() const
{
if (args[1]->const_item())
if (args[1]->const_item() && !args[1]->is_expensive())
{
String* res2= args[1]->val_str((String *)&cmp.value2);
const char *ptr2;