Jesus Camacho Rodriguez created HIVE-15524:
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Summary: Wrong result for LEFT outer join in Tez using
MapJoinOperator
Key: HIVE-15524
URL: https://issues.apache.org/jira/browse/HIVE-15524
Project: Hive
Issue Type: Bug
Affects Versions: 2.2.0
Reporter: Jesus Camacho Rodriguez
To reproduce, we can revert HIVE-15493 and run in Tez:
{code:sql}
set hive.auto.convert.join=true;
DROP TABLE IF EXISTS test_1;
CREATE TABLE test_1
(
member BIGINT
, age VARCHAR (100)
)
STORED AS TEXTFILE
;
DROP TABLE IF EXISTS test_2;
CREATE TABLE test_2
(
member BIGINT
)
STORED AS TEXTFILE
;
INSERT INTO test_1 VALUES (1, '20'), (2, '30'), (3, '40');
INSERT INTO test_2 VALUES (1), (2), (3);
SELECT
t2.member
, t1.age_1
, t1.age_2
FROM
test_2 t2
LEFT JOIN (
SELECT
member
, age as age_1
, age as age_2
FROM
test_1
) t1
ON t2.member = t1.member
;
{code}
Result is:
{noformat}
1 20 NULL
3 40 NULL
2 30 NULL
{noformat}
Correct result is:
{noformat}
1 20 20
3 40 40
2 30 30
{noformat}
Bug was introduced by HIVE-10582. Though the fix in HIVE-10582 does not contain
tests, it does look legit. In fact, the problem seems to be in the
MapJoinOperator itself. It only happens for LEFT outer join (not with RIGHT
outer or FULL outer). Although I am still trying to understand part of the
MapJoinOperator code path, the bug could be in the initialization of the
operator. It only happens when we have duplicate values in the right part of
the output.
HIVE-15493 provided a temporarily fix that removed the code in SemanticAnalyzer
that reuses duplicated value expressions from RS to create multiple columns in
the join output (this is equivalent to reverting HIVE-10582).
This follow-up issue should take the code back and tackle the problem in the
MapJoinOperator.
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