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MDEV-10236 Where expression with NOT function gives incorrect result

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Item_cache::is_null() erroneously returned null_value in a
non-cached state. Now Item_cache::is_null() uses has_value(),
which caches the value if not cached yet, similar to what other value methods do
(e.g. val_int, val_real, etc).
This commit is contained in:
Alexander Barkov 2016-06-28 13:11:04 +04:00
commit 56a3496067
3 changed files with 29 additions and 1 deletions
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17
mysql-test/r/null.result
View file

@ -1572,5 +1572,22 @@ SELECT * FROM t1 WHERE NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(N
i
DROP TABLE t1;
#
# MDEV-10236 Where expression with NOT function gives incorrect result
#
CREATE TABLE t1 (c1 INT);
INSERT INTO t1 VALUES (1),(2),(3);
EXPLAIN EXTENDED
SELECT * FROM t1 WHERE ((c1 IS NOT NULL) >= (NOT TRUE)) IS NOT NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Note 1003 select `test`.`t1`.`c1` AS `c1` from `test`.`t1` where (((`test`.`t1`.`c1` is not null) >= <cache>((not(1)))) is not null)
SELECT * FROM t1 WHERE ((c1 IS NOT NULL) >= (NOT TRUE)) IS NOT NULL;
c1
1
2
3
DROP TABLE t1;
#
# End of 10.1 tests
#

11
mysql-test/t/null.test
View file

@ -1007,6 +1007,17 @@ SELECT * FROM t1 WHERE NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(N
DROP TABLE t1;
--echo #
--echo # MDEV-10236 Where expression with NOT function gives incorrect result
--echo #
CREATE TABLE t1 (c1 INT);
INSERT INTO t1 VALUES (1),(2),(3);
EXPLAIN EXTENDED
SELECT * FROM t1 WHERE ((c1 IS NOT NULL) >= (NOT TRUE)) IS NOT NULL;
SELECT * FROM t1 WHERE ((c1 IS NOT NULL) >= (NOT TRUE)) IS NOT NULL;
DROP TABLE t1;
--echo #
--echo # End of 10.1 tests
--echo #

2
sql/item.h
View file

@ -5050,7 +5050,7 @@ public:
bool basic_const_item() const
{ return MY_TEST(example && example->basic_const_item()); }
virtual void clear() { null_value= TRUE; value_cached= FALSE; }
bool is_null() { return null_value; }
bool is_null() { return !has_value(); }
virtual bool is_expensive()
{
if (value_cached)