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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-2350) Improve RCFile Read Speed
Date Tue, 23 Aug 2011 07:46:29 GMT

    [ https://issues.apache.org/jira/browse/HIVE-2350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13089329#comment-13089329
] 

Hudson commented on HIVE-2350:
------------------------------

Integrated in Hive-trunk-h0.21 #909 (See [https://builds.apache.org/job/Hive-trunk-h0.21/909/])
    HIVE-2350. Improve RCFile Read Speed (Tim Armstrong via cws)

cws : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1160525
Files : 
* /hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/io/RCFile.java


> Improve RCFile Read Speed
> -------------------------
>
>                 Key: HIVE-2350
>                 URL: https://issues.apache.org/jira/browse/HIVE-2350
>             Project: Hive
>          Issue Type: Improvement
>          Components: Serializers/Deserializers
>            Reporter: Tim Armstrong
>            Assignee: Tim Armstrong
>            Priority: Minor
>              Labels: rcfile
>             Fix For: 0.8.0
>
>         Attachments: rcfile-2011-08-04.diff, rcfile_opt_2011-08-05.diff, rcfile_opt_2011-08-05b.diff,
rcfile_opt_2011-08-11.patch, rcfile_opt_2011-08-11.patch
>
>   Original Estimate: 0h
>  Remaining Estimate: 0h
>
> By tweaking the RCFile$Reader implementation to allow more efficient memory access I
was able to reduce CPU usage.  I measured the speed required to scan a gzipped RCFile, decompress
and assemble into records.  CPU time was reduced by about 7% for a full table scan,  An improvement
of about 2% was realised when a smaller subset of columns (3-5 out of tens) were selected.

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