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https://issues.apache.org/jira/browse/HIVE-2845?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13420673#comment-13420673
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Mahsa Mofidpoor commented on HIVE-2845:
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I've checked the query plan. It does not process joins. 
In this case the join key should be pushed to the mapper, but isn't it more 
appropriate to replace the TS operator(like HIVE-1694) rather than recompiling 
the query? 
                
> Add support for index joins in Hive
> -----------------------------------
>
>                 Key: HIVE-2845
>                 URL: https://issues.apache.org/jira/browse/HIVE-2845
>             Project: Hive
>          Issue Type: New Feature
>          Components: Indexing, Query Processor
>            Reporter: Namit Jain
>              Labels: indexing, joins, performance
>
> Hive supports indexes, which are used for filters currently.
> It would be very useful to add support for index-based joins in Hive.
> If 2 tables A and B are being joined, and an index exists on the join key of 
> A,
> B can be scanned (by the mappers), and for each row in B, a lookup for the 
> corresponding row in A can be performed.
> This can be very useful for some usecases.

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