[IMPALA-676] Left outer join returns incorrect results with IS NULL predicates in ON clause.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 1.2.1
• Fix Version/s: Impala 1.2.2
• Labels: correctness
• Assignee: Nong Li
• Reporter: Alexander Behm
• Created: 28/Nov/13 22:40
• Updated: 14/May/15 22:44
• Resolved: 06/Dec/13 21:27

Description

Repro:

create table test_join_a(x integer, y integer);
create table test_join_b(x integer, y integer);
insert into test_join_a values(null, 1);
insert into test_join_a values(null, 2);
insert into test_join_b values(null, 1);
insert into test_join_b values(null, 3);

select
    *
from test_join_a a left join test_join_b b
    on (a.x = b.x or (a.x is null and b.x is null)) and a.y = b.y;

Result of query (incorrect):
+------+---+------+------+
| x    | y | x    | y    |
+------+---+------+------+
| NULL | 2 | NULL | NULL |
| NULL | 1 | NULL | NULL |
+------+---+------+------+

Expected results:
+------+---+------+------+
| x    | y | x    | y    |
+------+---+------+------+
| NULL | 2 | NULL | NULL |
| NULL | 1 | NULL | 1    |
+------+---+------+------+