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https://issues.apache.org/jira/browse/HIVE-6430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13934692#comment-13934692
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Sergey Shelukhin commented on HIVE-6430:
----------------------------------------

Addressed all CR feedback, but patch still fails some Tez tests. Will address 
tomorrow.

Meanwhile, can you review common code (I may separate it into different patch), 
so that we could perhaps put this into Hive 13 in disabled form?

> MapJoin hash table has large memory overhead
> --------------------------------------------
>
>                 Key: HIVE-6430
>                 URL: https://issues.apache.org/jira/browse/HIVE-6430
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Sergey Shelukhin
>            Assignee: Sergey Shelukhin
>         Attachments: HIVE-6430.01.patch, HIVE-6430.patch
>
>
> Right now, in some queries, I see that storing e.g. 4 ints (2 for key and 2 
> for row) can take several hundred bytes, which is ridiculous. I am reducing 
> the size of MJKey and MJRowContainer in other jiras, but in general we don't 
> need to have java hash table there.  We can either use primitive-friendly 
> hashtable like the one from HPPC (Apache-licenced), or some variation, to map 
> primitive keys to single row storage structure without an object per row 
> (similar to vectorization).



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