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https://issues.apache.org/jira/browse/HIVE-2350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080091#comment-13080091
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jirapos...@reviews.apache.org commented on HIVE-2350:
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https://reviews.apache.org/r/1309/
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Review request for hive and Ning Zhang.
Summary
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By tweaking the RCFile$Reader implementation to allow more efficient memory
access I was able to reduce CPU usage. I measured the speed required to scan a
gzipped RCFile, decompress and assemble into records. CPU time was reduced by
about 7% for a full table scan, An improvement of about 2% was realised when a
smaller subset of columns (3-5 out of tens) were selected.
This addresses bug HIVE-2350.
https://issues.apache.org/jira/browse/HIVE-2350
Diffs
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trunk/ql/src/java/org/apache/hadoop/hive/ql/io/RCFile.java 1154070
Diff: https://reviews.apache.org/r/1309/diff
Testing
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Ran TestRCFile unit test. Manually tested reading from warehouse table.
Thanks,
Tim
> Improve RCFile Read Speed
> -------------------------
>
> Key: HIVE-2350
> URL: https://issues.apache.org/jira/browse/HIVE-2350
> Project: Hive
> Issue Type: Improvement
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Minor
> Attachments: rcfile-2011-08-04.diff, rcfile_opt_2011-08-05.diff
>
> Original Estimate: 0h
> Remaining Estimate: 0h
>
> By tweaking the RCFile$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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