Ankit Kamboj created HIVE-6520:
----------------------------------
Summary: Skew Join optimization doesn't work if parent gets
converted to MapJoin task
Key: HIVE-6520
URL: https://issues.apache.org/jira/browse/HIVE-6520
Project: Hive
Issue Type: Bug
Affects Versions: 0.11.0
Reporter: Ankit Kamboj
Skew join optimization (GenMRSkewJoinProcessor.java) assumes that its parent
stage(that will create directory structure for skewed keys) will have a Reduce
Join Operator. GenMRSkewJoinProcessor sets the "handleSkewJoin" flag only in
that case.
But it is possible that parent stage gets converted to MapJoin task (because of
hive.auto.convert.join flag). In that case "handleSkewJoin" is not set for
parent stage and it will not create directory structure for skewed keys in
hdfs. This eventually leads to elimination of skew join conditional task (and
its children) because the conditional task is not able to find the skewed key
directories.
Shouldn't the MapJoinOperator also handle skew join and create directory
structure for skewed keys in addition to performing map join for the non-skewed
keys?
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)
