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Fix bug lp:1008686

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Analysis:
The fix for bug lp:985667 implements the method Item_subselect::no_rows_in_result()
for all main kinds of subqueries. The purpose of this method is to be called from
return_zero_rows() and set Items to some default value in the case when a query
returns no rows. Aggregates and subqueries require special treatment in this case.

Every implementation of Item_subselect::no_rows_in_result() called
Item_subselect::make_const() to set the subquery predicate to its default value
irrespective of where the predicate was located in the query. Once the predicate
was set to a constant it was never executed.

At the same time, the JOIN object of the fake select for UNIONs (the one used for
the final result of the UNION), was set after all subqueries in the union were
executed. Since we set the subquery as constant, it was never executed, and the
corresponding JOIN was never created.

In order to decide whether the result of NOT IN is NULL or FALSE, Item_in_optimizer
needs to check if the subquery result was empty or not. This is where we got the
crash, because subselect_union_engine::no_rows() checks for
unit->fake_select_lex->join->send_records, and the join object was NULL.

Solution:
If a subquery is in the HAVING clause it must be evaluated in order to know its
result, so that we can properly filter the result records. Once subqueries in the
HAVING clause are executed even in the case of no result rows, this specific
crash will be solved, because the UNION will be executed, and its JOIN will be
constructed. Therefore the fix for this crash is to narrow the fix for lp:985667,
and to apply Item_subselect::no_rows_in_result() only when the subquery predicate
is in the SELECT clause.
This commit is contained in:
unknown 2012-06-15 11:33:24 +03:00
parent 88d3d853f4
commit db6dbadb5a
8 changed files with 177 additions and 6 deletions
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25
mysql-test/r/subselect.result
View File

@ -6112,5 +6112,30 @@ NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
f1 f2
drop table t1,t2;
#
# LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
# WHERE and UNION in HAVING
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 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
2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
min_a a
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 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
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
min_a a
drop table t1;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;

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

@ -6111,6 +6111,31 @@ NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
f1 f2
drop table t1,t2;
#
# LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
# WHERE and UNION in HAVING
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 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
2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
min_a a
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 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
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
min_a a
drop table t1;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set optimizer_switch=default;

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

@ -6107,6 +6107,31 @@ NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
f1 f2
drop table t1,t2;
#
# LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
# WHERE and UNION in HAVING
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 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
2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
min_a a
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 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
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
min_a a
drop table t1;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set @optimizer_switch_for_subselect_test=null;

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

@ -6118,6 +6118,31 @@ NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
f1 f2
drop table t1,t2;
#
# LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
# WHERE and UNION in HAVING
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 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
2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
min_a a
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 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
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
min_a a
drop table t1;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set optimizer_switch=default;

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

@ -6107,6 +6107,31 @@ NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
f1 f2
drop table t1,t2;
#
# LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
# WHERE and UNION in HAVING
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 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
2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 DEPENDENT UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
min_a a
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 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
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT UNION t1 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
min_a a
drop table t1;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set @optimizer_switch_for_subselect_test=null;

18
mysql-test/t/subselect.test
View File

@ -5190,5 +5190,23 @@ SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELE
drop table t1,t2;
--echo #
--echo # LP BUG#1008686 Server crashes in subselect_union_engine::no_rows on SELECT with impossible
--echo # WHERE and UNION in HAVING
--echo #
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(7);
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
SELECT MIN(a) AS min_a, a FROM t1 WHERE 0 HAVING a NOT IN ( SELECT 2 UNION SELECT 5 ) OR min_a != 1;
EXPLAIN
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
SELECT MIN(a) AS min_a, a FROM t1 WHERE 1=2 HAVING a NOT IN ( SELECT a from t1 UNION select a+1 from t1 ) OR min_a != 1;
drop table t1;
--echo # return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;

36
sql/item_subselect.cc
View File

@ -892,7 +892,14 @@ void Item_maxmin_subselect::print(String *str, enum_query_type query_type)
void Item_maxmin_subselect::no_rows_in_result()
{
if (const_item())
/*
Subquery predicates outside of the SELECT list must be evaluated in order
to possibly filter the special result row generated for implicit grouping
if the subquery is in the HAVING clause.
If the predicate is constant, we need its actual value in the only result
row for queries with implicit grouping.
*/
if (parsing_place != SELECT_LIST || const_item())
return;
value= Item_cache::get_cache(new Item_null());
null_value= 0;
@ -903,7 +910,14 @@ void Item_maxmin_subselect::no_rows_in_result()
void Item_singlerow_subselect::no_rows_in_result()
{
if (const_item())
/*
Subquery predicates outside of the SELECT list must be evaluated in order
to possibly filter the special result row generated for implicit grouping
if the subquery is in the HAVING clause.
If the predicate is constant, we need its actual value in the only result
row for queries with implicit grouping.
*/
if (parsing_place != SELECT_LIST || const_item())
return;
value= Item_cache::get_cache(new Item_null());
reset();
@ -1367,7 +1381,14 @@ Item* Item_exists_subselect::expr_cache_insert_transformer(uchar *thd_arg)
void Item_exists_subselect::no_rows_in_result()
{
if (const_item())
/*
Subquery predicates outside of the SELECT list must be evaluated in order
to possibly filter the special result row generated for implicit grouping
if the subquery is in the HAVING clause.
If the predicate is constant, we need its actual value in the only result
row for queries with implicit grouping.
*/
if (parsing_place != SELECT_LIST || const_item())
return;
value= 0;
null_value= 0;
@ -2713,7 +2734,14 @@ void Item_allany_subselect::print(String *str, enum_query_type query_type)
void Item_allany_subselect::no_rows_in_result()
{
if (const_item())
/*
Subquery predicates outside of the SELECT list must be evaluated in order
to possibly filter the special result row generated for implicit grouping
if the subquery is in the HAVING clause.
If the predicate is constant, we need its actual value in the only result
row for queries with implicit grouping.
*/
if (parsing_place != SELECT_LIST || const_item())
return;
value= 0;
null_value= 0;

4
sql/item_subselect.h
View File

@ -147,8 +147,8 @@ public:
null_value= 1;
}
/**
Set the subquery result to the default value for the predicate when the
subquery is known to produce an empty result.
Set the subquery result to a default value consistent with the semantics of
the result row produced for queries with implicit grouping.
*/
void no_rows_in_result()= 0;
virtual bool select_transformer(JOIN *join);