hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-13232) Aggressively drop compression buffers in ORC OutStreams
Date Tue, 08 Mar 2016 19:08:40 GMT

     [ https://issues.apache.org/jira/browse/HIVE-13232?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Owen O'Malley updated HIVE-13232:
---------------------------------
    Description: 
In Hive 0.11, when ORC's OutStream's were flushed they dropped all of the their buffers. In
the patch for HIVE-4243, 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.

  was:
In Hive 0.11, when ORC's OutStream's were flushed they dropped all of the their buffers. In
the patch for HIVE-4342, 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.


> 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
>
> In Hive 0.11, when ORC's OutStream's were flushed they dropped all of the their buffers.
In the patch for HIVE-4243, 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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message