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From "Yin Huai (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-3430) group by followed by join with the same key should be optimized
Date Wed, 05 Sep 2012 15:33:08 GMT

    [ https://issues.apache.org/jira/browse/HIVE-3430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13448825#comment-13448825
] 

Yin Huai commented on HIVE-3430:
--------------------------------

There is one thing I forgot to add in last comment...

The current patch of HIVE-2206 can only handle the simpler query example, because I let the
optimizer to check if the correlation can reach the bottom of the tree (i.e. input tables).
Since, in the original example, one of the group by operation on "value" starts from an intermediate
table, the current implementation cannot optimize that. But if two separate queries (one for
the join operations on "key" and another for the join and group by operations on "value",
as shown by the simpler example) are used, the current implementation should be able to optimize
the second one. The idea of YSmart covers the original example, but I have not implemented
it yet...
                
> group by followed by join with the same key should be optimized
> ---------------------------------------------------------------
>
>                 Key: HIVE-3430
>                 URL: https://issues.apache.org/jira/browse/HIVE-3430
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Namit Jain
>


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