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https://issues.apache.org/jira/browse/IMPALA-8279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16790091#comment-16790091
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ASF subversion and git services commented on IMPALA-8279:
---------------------------------------------------------
Commit 729fcf34764928bebfe7cf31153b57f7246404af in impala's branch
refs/heads/master from Andrew Sherman
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=729fcf3 ]
IMPALA-8279: Revert IMPALA-6658 to avoid ETL performance regression.
IMPALA-6658 changed RleEncoder to have the ability to use run lengths
other than 8. It seemed that a slightly more complex RleEncoder could
save a small amount of disk space by using the longer run lengths, in
particular for bit width of 1. We now see a performance regression on a
simple ETL query. Overall it seems that the costs of IMPALA-6658 exceed
the benefits. This change removes IMPALA-6658.
The strategy for this was that the change to rle-encoding.h, which
contains the code, was undone using 'git revert'. I removed the test
changes in rle-test.cc that rely on different encoding lengths. This
allows us to keep some useful new tests that were written as part of
IMPALA-6658
TESTING:
Ran all end-to-end tests.
Change-Id: If6bcbaf564fbbe6dc83ba3afc100b4e5ccc7af40
Reviewed-on: http://gerrit.cloudera.org:8080/12680
Reviewed-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
> Revert IMPALA-6658 to avoid ETL performance regression
> ------------------------------------------------------
>
> Key: IMPALA-8279
> URL: https://issues.apache.org/jira/browse/IMPALA-8279
> Project: IMPALA
> Issue Type: Bug
> Reporter: Andrew Sherman
> Priority: Major
>
> The fix for IMPALA-6658 seems to cause a measurable regression on
> {quote}
> use tpcds;
> create TABLE store_sales_unpart stored as parquet as SELECT * FROM
> tpcds.store_sales;
> INSERT OVERWRITE TABLE store_sales_unpart SELECT * FROM store_sales;
> {quote}
> Revert the change to avoid the regression.
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