Chao created HIVE-9025:
--------------------------
Summary: join38.q (without map join) produces incorrect result
when testing with multiple reducers
Key: HIVE-9025
URL: https://issues.apache.org/jira/browse/HIVE-9025
Project: Hive
Issue Type: Bug
Reporter: Chao
I have this query from a modified version of {{join38.q}}, which does NOT use
map join:
{code}
FROM src a JOIN tmp b ON (a.key = b.col11)
SELECT a.value, b.col5, count(1) as count
where b.col11 = 111
group by a.value, b.col5;
{code}
If I set {{mapred.reduce.tasks}} to 1, the result is correct. But, if I set it
to be a larger number (3 for instance), then result will be
{noformat}
val_111 105 1
{noformat}
which is wrong.
I think the issue is that, for this case, ConstantPropagationProcFactory will
overwrite the partition cols for the reduce sink desc, with an empty list.
Then, later on in ReduceSinkOperator#computeHashCode, since partitionEval is
length 0, it will use an random number as hashcode, for each separate row. As
result, rows with same key will be distributed to different reducers, and hence
leads to incorrect result.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
