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https://issues.apache.org/jira/browse/HIVE-2350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080056#comment-13080056
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Ning Zhang commented on HIVE-2350:
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Tim, can you post the diff to the review board (reviews.apache.org)? It's much
easier to review and adding comments for large diffs.
> 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
>
> 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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