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Fix bug lp:1002079

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Analysis:
  The optimizer detects an empty result through constant table optimization.
  Then it calls return_zero_rows(), which in turns calls inderctly
  Item_maxmin_subselect::no_rows_in_result(). The latter method set "value=0",
  however "value" is pointer to Item_cache, and not just an integer value.
  
  All of the Item_[maxmin | singlerow]_subselect::val_XXX methods does:
    if (forced_const)
      return value->val_real();
  which of course crashes when value is a NULL pointer.
  
  Solution:
  When the optimizer discovers an empty result set, set
  Item_singlerow_subselect::value to a FALSE constant Item instead of NULL.
This commit is contained in:
unknown
2012-05-22 15:22:55 +03:00
parent b87ccfdfbc
commit 02bdc608b5
8 changed files with 115 additions and 2 deletions
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18
mysql-test/r/subselect.result
View File

@ -6094,5 +6094,23 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
COUNT(f1) f4
0 0
drop table t1,t2;
#
# LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
# HAVING, UNION in subquery
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 0 const row not found
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;

18
mysql-test/r/subselect_no_mat.result
View File

@ -6093,6 +6093,24 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
COUNT(f1) f4
0 0
drop table t1,t2;
#
# LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
# HAVING, UNION in subquery
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 0 const row not found
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set optimizer_switch=default;

18
mysql-test/r/subselect_no_opts.result
View File

@ -6089,6 +6089,24 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
COUNT(f1) f4
0 0
drop table t1,t2;
#
# LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
# HAVING, UNION in subquery
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 0 const row not found
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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;
# 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/r/subselect_no_scache.result
View File

@ -6100,6 +6100,24 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
COUNT(f1) f4
0 0
drop table t1,t2;
#
# LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
# HAVING, UNION in subquery
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 0 const row not found
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set optimizer_switch=default;

18
mysql-test/r/subselect_no_semijoin.result
View File

@ -6089,6 +6089,24 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
COUNT(f1) f4
0 0
drop table t1,t2;
#
# LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
# HAVING, UNION in subquery
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 0 const row not found
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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;
# return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;
set @optimizer_switch_for_subselect_test=null;

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

@ -5174,6 +5174,21 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
drop table t1,t2;
--echo #
--echo # LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
--echo # HAVING, UNION in subquery
--echo #
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (7),(0);
CREATE TABLE t2 (b INT);
EXPLAIN
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
drop table t1,t2;
--echo # return optimizer switch changed in the beginning of this test
set optimizer_switch=@subselect_tmp;

10
sql/item_subselect.cc
View File

@ -892,13 +892,21 @@ void Item_maxmin_subselect::print(String *str, enum_query_type query_type)
void Item_maxmin_subselect::no_rows_in_result()
{
value= 0;
value= Item_cache::get_cache(new Item_null());
null_value= 0;
was_values= 0;
make_const();
}
void Item_singlerow_subselect::no_rows_in_result()
{
value= Item_cache::get_cache(new Item_null());
reset();
make_const();
}
void Item_singlerow_subselect::reset()
{
Item_subselect::reset();

2
sql/item_subselect.h
View File

@ -267,7 +267,7 @@ public:
subs_type substype() { return SINGLEROW_SUBS; }
void reset();
void no_rows_in_result() { reset(); make_const(); }
void no_rows_in_result();
bool select_transformer(JOIN *join);
void store(uint i, Item* item);
double val_real();