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Posted to dev@hive.apache.org by "Tim Armstrong (JIRA)" <ji...@apache.org> on 2011/08/05 05:03:28 UTC

[jira] [Updated] (HIVE-2350) Improve RCFile Read Speed

     [ https://issues.apache.org/jira/browse/HIVE-2350?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong updated HIVE-2350:
--------------------------------

    Status: Patch Available  (was: Open)

> 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
>   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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