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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/1309/
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(Updated 2011-08-05 19:58:03.986031)
Review request for hive and Ning Zhang.
Changes
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Made some further optimisations to reduce branches and condition checks in the
innermost loop, reducing CPU usage in getCurrentRow by about 20-25%, giving a
few % more improvement overall for table scans.
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 (updated)
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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
