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https://issues.apache.org/jira/browse/HIVE-2284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13066395#comment-13066395
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Hudson commented on HIVE-2284:
------------------------------
Integrated in Hive-trunk-h0.21 #829 (See
[https://builds.apache.org/job/Hive-trunk-h0.21/829/])
HIVE-2284 Bucketized map join should allow join key as a superset of
bucketized columns (Ning Zhang via namit)
namit : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1147364
Files :
* /hive/trunk/contrib/build.xml
* /hive/trunk/eclipse-templates/.classpath
* /hive/trunk/ql/src/test/results/clientpositive/smb_mapjoin_10.q.out
*
/hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/optimizer/BucketMapJoinOptimizer.java
* /hive/trunk/ql/src/test/queries/clientpositive/smb_mapjoin_10.q
> bucketized map join should allow join key as a superset of bucketized columns
> -----------------------------------------------------------------------------
>
> Key: HIVE-2284
> URL: https://issues.apache.org/jira/browse/HIVE-2284
> Project: Hive
> Issue Type: Improvement
> Reporter: Ning Zhang
> Assignee: Ning Zhang
> Fix For: 0.8.0
>
> Attachments: HIVE-2284.patch
>
>
> Currently bucketized mapjoin only allow the join keys being exactly the same
> as bucketized columns. This is too restrictive and is missing some
> optimization opportunities.
> If tables S and T are both bucketized on column A with the same # of buckets,
> and the query is something like:
> <code>
> SELECT /*+ MAPJOIN (S) */ ...
> FROM S join T
> ON (S.A = T.A AND S.B = T.B)
> <code>
> We should allow bucketized mapjoin since it's straightforward that bucket 1
> from S join with bucket 2 from T on such join condition must be empty.
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