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Fixed bug #49600.

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The problem could be demonstrated with an outer join of two single-row
tables where the values of the join attributes were null. Any query
with such a join could return a wrong result set if the where
condition of the query was not empty. For queries with empty
where conditions the result sets were correct.
This was the consequence of two bugs in the code:
 - Item_equal objects for on conditions of outer joins were
   not built if the processed query had no where condition
 - the check for null values in the code that evaluated constant 
   Item_equal objects was incorrect.
Fixed both above problems.
Added a test case for the bug and adjusted results for some other
test cases.
This commit is contained in:
Igor Babaev
2010-09-11 08:20:35 -07:00
parent 6f59c41d2d
commit 577b7345c7
7 changed files with 49 additions and 17 deletions
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14
mysql-test/r/join_outer.result
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@ -1397,4 +1397,18 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
Warnings:
Note 1003 select straight_join `test`.`jt1`.`f1` AS `f1` from `test`.`t1` `jt6` left join (`test`.`t1` `jt3` join `test`.`t1` `jt4` left join `test`.`t1` `jt5` on(1) left join `test`.`t1` `jt2` on(1)) on((`test`.`jt6`.`f1` and 1)) left join `test`.`t1` `jt1` on(1) where 1
DROP TABLE t1;
#
# Bug#49600: outer join of two single-row tables with joining attributes
# evaluated to nulls
create table t1 (a int, b int);
create table t2 (a int, b int);
insert into t1 values (1, NULL);
insert into t2 values (2, NULL);
select * from t1 left join t2 on t1.b=t2.b;
a b a b
1 NULL NULL NULL
select * from t1 left join t2 on t1.b=t2.b where 1=1;
a b a b
1 NULL NULL NULL
drop table t1,t2;
End of 5.1 tests