MR-2450 introduced a significant performance regression
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Key: MAPREDUCE-3768
URL: https://issues.apache.org/jira/browse/MAPREDUCE-3768
Project: Hadoop Map/Reduce
Issue Type: Bug
Components: mrv2
Affects Versions: 0.23.1
Reporter: Eli Collins
Priority: Blocker
MAPREDUCE-2450 introduced, or at least triggers, a significant performance
regression in Hive. With MR-2450 the execution time of TestCliDriver.skewjoin
goes from 2 minutes to 15 minutes. Reverting this change from the build fixes
the issue.
Here's the relevant query:
{noformat}
FROM src src1 JOIN src src2 ON (src1.key = src2.key)
INSERT OVERWRITE TABLE dest_j1 SELECT src1.key, src2.value;
{noformat}
You can reproduce this by running the following from Hive 8.0 against Hadoop
built from branch-23.
{noformat}
ant very-clean package test -Dtestcase=TestCliDriver -Dqfile=skewjoin.q
{noformat}
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