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MDEV-3899 Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT

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Analysys:
In the beginning of JOIN::cleanup there is code that is supposed to
free all filesort buffers. The code assumes that the table being sorted
is the first non-constant table. To get this table it calls:
first_top_level_tab(this, WITHOUT_CONST_TABLES)
  
However, first_top_level_tab() instead returned the wrong table - the first
one in the plan, instead of the first non-constant table. There is no other
place outside filesort() where sort buffers may be freed. As a result, the
sort buffer was not freed, and there was a memory leak.
  
Solution:
Change first_top_level_tab(), to test for WITH_CONST_TABLES instead of
WITHOUT_CONST_TABLES.
This commit is contained in:
unknown
2012-12-20 22:38:40 +02:00
parent 35b6020835
commit 1b2692d0e9
3 changed files with 30 additions and 2 deletions
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13
mysql-test/r/subselect4.result
View File

@@ -2247,5 +2247,18 @@ MAX(a) bb
NULL NULL NULL NULL
drop table t1, t2; drop table t1, t2;
set optimizer_switch=@subselect4_tmp; set optimizer_switch=@subselect4_tmp;
#
# MDEV-3899 Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT
#
CREATE TABLE t1 (a INT) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1),(9);
CREATE TABLE t2 (b INT) ENGINE=MyISAM;
INSERT INTO t2 VALUES (8);
SELECT * FROM t1
WHERE (1, 1) IN (SELECT a, SUM(DISTINCT a) FROM t1, t2 GROUP BY a);
a
1
9
drop table t1, t2;
SET optimizer_switch= @@global.optimizer_switch; SET optimizer_switch= @@global.optimizer_switch;
set @@tmp_table_size= @@global.tmp_table_size; set @@tmp_table_size= @@global.tmp_table_size;

15
mysql-test/t/subselect4.test
View File

@@ -1777,5 +1777,20 @@ drop table t1, t2;
set optimizer_switch=@subselect4_tmp; set optimizer_switch=@subselect4_tmp;
--echo #
--echo # MDEV-3899 Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT
--echo #
CREATE TABLE t1 (a INT) ENGINE=MyISAM;
INSERT INTO t1 VALUES (1),(9);
CREATE TABLE t2 (b INT) ENGINE=MyISAM;
INSERT INTO t2 VALUES (8);
SELECT * FROM t1
WHERE (1, 1) IN (SELECT a, SUM(DISTINCT a) FROM t1, t2 GROUP BY a);
drop table t1, t2;
SET optimizer_switch= @@global.optimizer_switch; SET optimizer_switch= @@global.optimizer_switch;
set @@tmp_table_size= @@global.tmp_table_size; set @@tmp_table_size= @@global.tmp_table_size;

4
sql/sql_select.cc
View File

@@ -7333,10 +7333,10 @@ JOIN_TAB *next_breadth_first_tab(JOIN *join, enum enum_exec_or_opt tabs_kind,
} }
JOIN_TAB *first_top_level_tab(JOIN *join, enum enum_with_const_tables with_const) JOIN_TAB *first_top_level_tab(JOIN *join, enum enum_with_const_tables const_tbls)
{ {
JOIN_TAB *tab= join->join_tab; JOIN_TAB *tab= join->join_tab;
if (with_const == WITH_CONST_TABLES) if (const_tbls == WITHOUT_CONST_TABLES)
{ {
if (join->const_tables == join->table_count) if (join->const_tables == join->table_count)
return NULL; return NULL;