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MDEV-17066: Bytes lost or Assertion `status_var.local_memory_used == 0 after DELETE with subquery with ROLLUP

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The issue here is when records are read from the temporary file
(filesort result in this case) via a cache(rr_from_cache).
The cache is initialized with init_rr_cache.
For correlated subquery the cache allocation is happening at each execution
of the subquery but the deallocation happens only once and that was
when the query execution was done.

So generally for subqueries we do two types of cleanup

1) Full cleanup: we should free all resources of the query(like temp tables).
   This is done generally when the query execution is complete or the subquery
   re-execution is not needed (case with uncorrelated subquery)

2) Partial cleanup: Minor cleanup that is required if
   the subquery needs recalculation. This is done for all the structures that
   need to be allocated for each execution (example SORT_INFO for filesort
   is allocated for each execution of the correlated subquery).

The fix here would be free the cache used by rr_from_cache in the partial
cleanup phase.
This commit is contained in:
Varun Gupta
2020-07-23 14:17:05 +05:30
parent 91caf130b7
commit 1e31d74833
6 changed files with 99 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
mysql-test/r/subselect4.result
View File

@ -2620,4 +2620,29 @@ SELECT (SELECT DISTINCT t1i.b FROM t1 t1i GROUP BY t1i.a ORDER BY MAX(t1o.b)) FR
0
SET @@optimizer_switch= @save_optimizer_switch;
DROP TABLE t1;
#
# MDEV-17066: Bytes lost or Assertion `status_var.local_memory_used == 0 after DELETE
# with subquery with ROLLUP
#
CREATE TABLE t1 (i INT DEFAULT 0, c VARCHAR(2048));
INSERT INTO t1 SELECT 0, seq FROM seq_1_to_6000;
CREATE TABLE t2 (f VARCHAR(2048) DEFAULT '');
INSERT INTO t2 VALUES ('1'),('bar');
EXPLAIN
SELECT * FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 6000 Using filesort
SELECT * FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP);
f
1
SELECT * FROM t2;
f
1
bar
DELETE FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP );
SELECT * FROM t2;
f
bar
DROP TABLE t1, t2;
# End of 10.2 tests

23
mysql-test/t/subselect4.test
View File

@ -7,6 +7,8 @@ drop table if exists t0,t1,t2,t3,t4,t5,t6;
drop view if exists v1, v2;
--enable_warnings
--source include/have_sequence.inc
set @subselect4_tmp= @@optimizer_switch;
set optimizer_switch='semijoin=on,firstmatch=on,loosescan=on';
set optimizer_switch='semijoin_with_cache=on';
@ -2153,4 +2155,25 @@ SELECT (SELECT DISTINCT t1i.b FROM t1 t1i GROUP BY t1i.a ORDER BY MAX(t1o.b)) FR
SET @@optimizer_switch= @save_optimizer_switch;
DROP TABLE t1;
--echo #
--echo # MDEV-17066: Bytes lost or Assertion `status_var.local_memory_used == 0 after DELETE
--echo # with subquery with ROLLUP
--echo #
CREATE TABLE t1 (i INT DEFAULT 0, c VARCHAR(2048));
INSERT INTO t1 SELECT 0, seq FROM seq_1_to_6000;
CREATE TABLE t2 (f VARCHAR(2048) DEFAULT '');
INSERT INTO t2 VALUES ('1'),('bar');
EXPLAIN
SELECT * FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP);
SELECT * FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP);
SELECT * FROM t2;
DELETE FROM t2 WHERE f IN ( SELECT MAX(c) FROM t1 GROUP BY c WITH ROLLUP );
SELECT * FROM t2;
DROP TABLE t1, t2;
--echo # End of 10.2 tests

20
sql/records.cc
View File

@ -320,12 +320,9 @@ bool init_read_record(READ_RECORD *info,THD *thd, TABLE *table,
void end_read_record(READ_RECORD *info)
{ /* free cache if used */
if (info->cache)
{
my_free_lock(info->cache);
info->cache=0;
}
{
/* free cache if used */
free_cache(info);
if (info->table)
{
if (info->table->is_created())
@ -336,6 +333,17 @@ void end_read_record(READ_RECORD *info)
}
}
void free_cache(READ_RECORD *info)
{
if (info->cache)
{
my_free_lock(info->cache);
info->cache=0;
}
}
static int rr_handle_error(READ_RECORD *info, int error)
{
if (info->thd->killed)

1
sql/records.h
View File

@ -30,6 +30,7 @@ class SORT_INFO;
struct READ_RECORD;
void end_read_record(READ_RECORD *info);
void free_cache(READ_RECORD *info);
/**
A context for reading through a single table using a chosen access method:

53
sql/sql_select.cc
View File

@ -12391,24 +12391,7 @@ void JOIN::cleanup(bool full)
for (tab= first_linear_tab(this, WITH_BUSH_ROOTS, WITH_CONST_TABLES); tab;
tab= next_linear_tab(this, tab, WITH_BUSH_ROOTS))
{
if (!tab->table)
continue;
DBUG_PRINT("info", ("close index: %s.%s alias: %s",
tab->table->s->db.str,
tab->table->s->table_name.str,
tab->table->alias.c_ptr()));
if (tab->table->is_created())
{
tab->table->file->ha_index_or_rnd_end();
if (tab->aggr)
{
int tmp= 0;
if ((tmp= tab->table->file->extra(HA_EXTRA_NO_CACHE)))
tab->table->file->print_error(tmp, MYF(0));
}
}
delete tab->filesort_result;
tab->filesort_result= NULL;
tab->partial_cleanup();
}
}
}
@ -26982,6 +26965,40 @@ void JOIN::handle_implicit_grouping_with_window_funcs()
}
}
/*
@brief
Perform a partial cleanup for the JOIN_TAB structure
@note
this is used to cleanup resources for the re-execution of correlated
subqueries.
*/
void JOIN_TAB::partial_cleanup()
{
if (!table)
return;
if (table->is_created())
{
table->file->ha_index_or_rnd_end();
DBUG_PRINT("info", ("close index: %s.%s alias: %s",
table->s->db.str,
table->s->table_name.str,
table->alias.c_ptr()));
if (aggr)
{
int tmp= 0;
if ((tmp= table->file->extra(HA_EXTRA_NO_CACHE)))
table->file->print_error(tmp, MYF(0));
}
}
delete filesort_result;
filesort_result= NULL;
free_cache(&read_record);
}
/**
@} (end of group Query_Optimizer)
*/

2
sql/sql_select.h
View File

@ -613,7 +613,7 @@ typedef struct st_join_table {
bool use_order() const; ///< Use ordering provided by chosen index?
bool sort_table();
bool remove_duplicates();
void partial_cleanup();
} JOIN_TAB;