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https://issues.apache.org/jira/browse/HIVE-2845?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13420466#comment-13420466
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He Yongqiang commented on HIVE-2845:
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With HIVE-1644, this should be done. Have you looked at the query plan, or 
looked at the patch of HIVE-1644? Maybe Hive-1644 does not process join cases 
(but the code is already there.) The filter needs to be pushed down to the 
mapper to trigger the auto index.

                
> 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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