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Date: Wed, 12 Mar 2014 02:31:43 +0000 (UTC)
From: "Sergey Shelukhin (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12695140.1392352448626.48658.1394591503030@arcas>
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Subject: [jira] [Updated] (HIVE-6430) MapJoin hash table has large memory
 overhead
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     [ https://issues.apache.org/jira/browse/HIVE-6430?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sergey Shelukhin updated HIVE-6430:
-----------------------------------

    Attachment: HIVE-6430.01.patch

most of RB feedback except for refactor, need to discuss... also added ascii art to comments and one more memory optimization to truncate the array, after initial tests.

> 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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