[jira] [Commented] (HIVE-6430) MapJoin hash table has large memory overhead

["Sergey Shelukhin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-6430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13918915#comment-13918915 ] 

Sergey Shelukhin commented on HIVE-6430:
----------------------------------------

wrong jira

> 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
>
> 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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