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https://issues.apache.org/jira/browse/HIVE-2350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13087352#comment-13087352
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Tim Armstrong commented on HIVE-2350:
-------------------------------------
Hi Carl,
Was this committed to trunk? I'm not seeing it there
> Improve RCFile Read Speed
> -------------------------
>
> Key: HIVE-2350
> URL: https://issues.apache.org/jira/browse/HIVE-2350
> Project: Hive
> Issue Type: Improvement
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Minor
> 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
>
> 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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