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Date: Tue, 18 Feb 2014 18:56:19 +0000 (UTC)
From: "Sergey Shelukhin (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12695139.1392352180208.58895.1392749779043@arcas>
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Subject: [jira] [Commented] (HIVE-6429) MapJoinKey has large memory overhead
 in typical cases
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    [ https://issues.apache.org/jira/browse/HIVE-6429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13904404#comment-13904404 ] 

Sergey Shelukhin commented on HIVE-6429:
----------------------------------------

https://reviews.apache.org/r/18230/

> 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.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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