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From "Gunther Hagleitner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6429) MapJoinKey has large memory overhead in typical cases
Date Fri, 21 Feb 2014 04:46:19 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13907953#comment-13907953
] 

Gunther Hagleitner commented on HIVE-6429:
------------------------------------------

partial review on rb.

> MapJoinKey has large memory overhead in typical cases
> -----------------------------------------------------
>
>                 Key: HIVE-6429
>                 URL: https://issues.apache.org/jira/browse/HIVE-6429
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Sergey Shelukhin
>            Assignee: Sergey Shelukhin
>         Attachments: HIVE-6429.01.patch, HIVE-6429.02.patch, HIVE-6429.WIP.patch, HIVE-6429.patch
>
>
> The only thing that MJK really needs it hashCode and equals (well, and construction),
so there's no need to have array of writables in there. Assuming all the keys for a table
have the same structure, for the common case where keys are primitive types, we can store
something like a byte array combination of keys to reduce the memory usage. Will probably
speed up compares too.



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