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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-13232) Aggressively drop compression buffers in ORC OutStreams
Date Fri, 11 Mar 2016 18:55:38 GMT

    [ https://issues.apache.org/jira/browse/HIVE-13232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15191380#comment-15191380
] 

Prasanth Jayachandran commented on HIVE-13232:
----------------------------------------------

LGTM,+1

> Aggressively drop compression buffers in ORC OutStreams
> -------------------------------------------------------
>
>                 Key: HIVE-13232
>                 URL: https://issues.apache.org/jira/browse/HIVE-13232
>             Project: Hive
>          Issue Type: Bug
>          Components: ORC
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>             Fix For: 0.14.1, 1.3.0, 2.1.0
>
>         Attachments: HIVE-13232.patch
>
>
> In Hive 0.11, when ORC's OutStream's were flushed they dropped all of the their buffers.
In the patch for HIVE-4324, we inadvertently changed that behavior so that one of the buffers
is held on to. For queries with a lot of writers and thus under significant memory pressure
this can have a significant impact on the memory usage. 
> Note that "hive.optimize.sort.dynamic.partition" avoids this problem by sorting on the
dynamic partition key and thus only a single ORC writer is open at once. This will use memory
more effectively and avoid creating ORC files with very small stripes, which will produce
better downstream performance.



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