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Fix bug lp:782305

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Analysis:
Both the wrong result and the valgrind warning were a result
of incomplete cleanup of the MIN/MAX subquery rewrite. At the
first execution of the query, the non-aggregate subquery is
transformed into an aggregate MIN/MAX subquery. During the
fix_fields phase of the MIN/MAX function, it sets the property
st_select_lex::with_sum_func to true.

The second execution of the query finds this flag to be ON.
When optimization reaches the same MIN/MAX subquery
transformation, it tests if the subquery is an aggregate or not.
Since select_lex->with_sum_func == true from the previous
execution, the transformation executes the second branch that
handles aggregate subqueries. This substitutes the subquery
Item into a Item_maxmin_subselect. At the same time elsewhere
it is assumed that the subquery Item is of type
Item_allany_subselect. Ultimately this results in casting the
actual object to the wrong class, and calling the wrong
any_value() method from empty_underlying_subquery().

Solution:
Cleanup the st_select_lex::with_sum_func property in the case
when the MIN/MAX transformation was performed for a non-aggregate
subquery, so that the transformation can be repeated.
This commit is contained in:
unknown
2011-07-18 23:45:38 +03:00
parent cc0195d6a1
commit c9e236828e
5 changed files with 94 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
mysql-test/r/subselect4.result
View File

@ -2060,4 +2060,34 @@ WHERE t1.f4 IN ( SELECT f4 FROM t2 ) ;
f4
set @@optimizer_switch = @old_optimizer_switch;
drop table t1, t2, t3;
#
# LP BUG#782305: Wrong result/valgrind warning in Item_sum_hybrid::any_value()
#
CREATE TABLE t1 ( f1 int) ;
INSERT INTO t1 VALUES (2),(3);
CREATE TABLE t2 (f2 int) ;
INSERT INTO t2 VALUES (2),(3);
PREPARE st1 FROM '
SELECT * FROM t2
WHERE f2 <= SOME ( SELECT f1 FROM t1 );
';
EXECUTE st1;
f2
2
3
EXECUTE st1;
f2
2
3
PREPARE st2 FROM '
SELECT * FROM t2
WHERE f2 <= SOME (SELECT f1-2 FROM t1 UNION SELECT f1-1 FROM t1);
';
EXECUTE st2;
f2
2
EXECUTE st2;
f2
2
drop table t1, t2;
set optimizer_switch=@subselect4_tmp;

27
mysql-test/t/subselect4.test
View File

@ -1700,4 +1700,31 @@ set @@optimizer_switch = @old_optimizer_switch;
drop table t1, t2, t3;
--echo #
--echo # LP BUG#782305: Wrong result/valgrind warning in Item_sum_hybrid::any_value()
--echo #
CREATE TABLE t1 ( f1 int) ;
INSERT INTO t1 VALUES (2),(3);
CREATE TABLE t2 (f2 int) ;
INSERT INTO t2 VALUES (2),(3);
PREPARE st1 FROM '
SELECT * FROM t2
WHERE f2 <= SOME ( SELECT f1 FROM t1 );
';
EXECUTE st1;
EXECUTE st1;
PREPARE st2 FROM '
SELECT * FROM t2
WHERE f2 <= SOME (SELECT f1-2 FROM t1 UNION SELECT f1-1 FROM t1);
';
EXECUTE st2;
EXECUTE st2;
drop table t1, t2;
set optimizer_switch=@subselect4_tmp;

38
sql/item_subselect.cc
View File

@ -167,6 +167,23 @@ void Item_in_subselect::cleanup()
DBUG_VOID_RETURN;
}
void Item_allany_subselect::cleanup()
{
/*
The MAX/MIN transformation through injection is reverted through the
change_item_tree() mechanism. Revert the select_lex object of the
query to its initial state.
*/
for (SELECT_LEX *sl= unit->first_select();
sl; sl= sl->next_select())
if (in_strategy & SUBS_MAXMIN_INJECTED)
sl->with_sum_func= false;
Item_in_subselect::cleanup();
}
Item_subselect::~Item_subselect()
{
DBUG_ENTER("Item_subselect::~Item_subselect");
@ -1566,7 +1583,7 @@ Item_in_subselect::single_value_transformer(JOIN *join)
bool Item_allany_subselect::transform_into_max_min(JOIN *join)
{
DBUG_ENTER("Item_allany_subselect::transform_into_max_min");
if (!(in_strategy & SUBS_MAXMIN))
if (!(in_strategy & (SUBS_MAXMIN_INJECTED | SUBS_MAXMIN_ENGINE)))
DBUG_RETURN(false);
Item **place= optimizer->arguments() + 1;
THD *thd= join->thd;
@ -1626,6 +1643,12 @@ bool Item_allany_subselect::transform_into_max_min(JOIN *join)
if (join->prepare_stage2())
DBUG_RETURN(true);
subs= new Item_singlerow_subselect(select_lex);
/*
Remove other strategies if any (we already changed the query and
can't apply other strategy).
*/
in_strategy= SUBS_MAXMIN_INJECTED;
}
else
{
@ -1633,6 +1656,11 @@ bool Item_allany_subselect::transform_into_max_min(JOIN *join)
subs= item= new Item_maxmin_subselect(thd, this, select_lex, func->l_op());
if (upper_item)
upper_item->set_sub_test(item);
/*
Remove other strategies if any (we already changed the query and
can't apply other strategy).
*/
in_strategy= SUBS_MAXMIN_ENGINE;
}
/* fix fields is already called for left expression */
subs= func->create(left_expr, subs);
@ -1643,11 +1671,6 @@ bool Item_allany_subselect::transform_into_max_min(JOIN *join)
select_lex->master_unit()->uncacheable&= ~UNCACHEABLE_DEPENDENT_INJECTED;
select_lex->uncacheable&= ~UNCACHEABLE_DEPENDENT_INJECTED;
/*
Remove other strategies if there was (we already changed the query and
can't apply other strategy).
*/
in_strategy= SUBS_MAXMIN;
DBUG_RETURN(false);
}
@ -2540,7 +2563,8 @@ bool
Item_allany_subselect::select_transformer(JOIN *join)
{
DBUG_ENTER("Item_allany_subselect::select_transformer");
DBUG_ASSERT((in_strategy & ~(SUBS_MAXMIN | SUBS_IN_TO_EXISTS)) == 0);
DBUG_ASSERT((in_strategy & ~(SUBS_MAXMIN_INJECTED | SUBS_MAXMIN_ENGINE |
SUBS_IN_TO_EXISTS)) == 0);
in_strategy|= SUBS_IN_TO_EXISTS;
if (upper_item)
upper_item->show= 1;

6
sql/item_subselect.h
View File

@ -366,7 +366,10 @@ TABLE_LIST * const NO_JOIN_NEST=(TABLE_LIST*)0x1;
#define SUBS_PARTIAL_MATCH_ROWID_MERGE 8
#define SUBS_PARTIAL_MATCH_TABLE_SCAN 16
/* ALL/ANY will be transformed with max/min optimization */
#define SUBS_MAXMIN 32
/* The subquery has not aggregates, transform it into a MAX/MIN query. */
#define SUBS_MAXMIN_INJECTED 32
/* The subquery has aggregates, use a special max/min subselect engine. */
#define SUBS_MAXMIN_ENGINE 64
/**
@ -555,6 +558,7 @@ public:
Item_allany_subselect(Item * left_expr, chooser_compare_func_creator fc,
st_select_lex *select_lex, bool all);
void cleanup();
// only ALL subquery has upper not
subs_type substype() { return all?ALL_SUBS:ANY_SUBS; }
bool select_transformer(JOIN *join);

2
sql/opt_subselect.cc
View File

@ -466,7 +466,7 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
/* Check if max/min optimization applicable */
if (allany_subs)
allany_subs->in_strategy|= (allany_subs->is_maxmin_applicable(join) ?
SUBS_MAXMIN :
(SUBS_MAXMIN_INJECTED | SUBS_MAXMIN_ENGINE) :
SUBS_IN_TO_EXISTS);
/*