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Posted to issues@hive.apache.org by "Prasanth Jayachandran (JIRA)" <ji...@apache.org> on 2016/03/11 19:55:38 UTC
[jira] [Commented] (HIVE-13232) Aggressively drop compression
buffers in ORC OutStreams
[ 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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