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