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Bug #54190: Comparison to row subquery produces incorrect

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result

Row subqueries producing no rows were not handled as UNKNOWN
values in row comparison expressions.

That was a result of the following two problems:

1. Item_singlerow_subselect did not mark the resulting row
value as NULL/UNKNOWN when no rows were produced.

2. Arg_comparator::compare_row() did not take into account that
a whole argument may be NULL rather than just individual scalar
values.

Before bug#34384 was fixed, the above problems were hidden
because an uninitialized (i.e. without any stored value) cached
object would appear as NULL for scalar values in a row subquery
returning an empty result. After the fix
Arg_comparator::compare_row() would try to evaluate
uninitialized cached objects.

Fixed by removing the aforementioned problems.


mysql-test/r/row.result:
  Added a test case for bug #54190.
mysql-test/r/subselect.result:
  Updated the result for a test relying on wrong behavior.
mysql-test/t/row.test:
  Added a test case for bug #54190.
sql/item_cmpfunc.cc:
  If either of the argument rows is NULL, return NULL as the
  result of comparison.
sql/item_subselect.cc:
  Adjust null_value for Item_singlerow_subselect depending on
  whether a row has been produced by the row subquery.
This commit is contained in:
Alexey Kopytov
2010-09-09 16:46:13 +04:00
parent 8822ecff2d
commit 453107bc56
5 changed files with 55 additions and 3 deletions
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4
mysql-test/r/subselect.result
View File

@ -922,7 +922,7 @@ select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a'),(select c from t
a (select a,b,c from t1 where t1.a=t2.a) = ROW(a,2,'a') (select c from t1 where a=t2.a)
1 1 a
2 0 b
NULL 0 NULL
NULL NULL NULL
select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b'),(select c from t1 where a=t2.a) from t2;
a (select a,b,c from t1 where t1.a=t2.a) = ROW(a,3,'b') (select c from t1 where a=t2.a)
1 0 a
@ -932,7 +932,7 @@ select a, (select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c'),(select c from t
a (select a,b,c from t1 where t1.a=t2.a) = ROW(a,4,'c') (select c from t1 where a=t2.a)
1 0 a
2 0 b
NULL 0 NULL
NULL NULL NULL
drop table t1,t2;
create table t1 (a int, b real, c varchar(10));
insert into t1 values (1, 1, 'a'), (2,2,'b'), (NULL, 2, 'b');