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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-2284) bucketized map join should allow join key as a superset of bucketized columns
Date Sat, 16 Jul 2011 10:39:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-2284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13066395#comment-13066395
] 

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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