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https://issues.apache.org/jira/browse/TAJO-36?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13890508#comment-13890508
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Tajo QA commented on TAJO-36:
-----------------------------
{color:red}*-1 overall.*{color} Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12626845/TAJO-36_140204_172847.patch
against master revision 51919cf.
{color:green}+1 @author.{color} The patch does not contain any @author
tags.
{color:green}+1 tests included.{color} The patch appears to include 14 new
or modified test files.
{color:green}+1 javac.{color} The applied patch does not increase the
total number of javac compiler warnings.
{color:green}+1 javadoc.{color} The applied patch does not increase the
total number of javadoc warnings.
{color:green}+1 checkstyle.{color} The patch generated 0 code style errors.
{color:red}-1 findbugs.{color} The patch appears to introduce 212 new
Findbugs (version 1.3.9) warnings.
{color:green}+1 release audit.{color} The applied patch does not increase
the total number of release audit warnings.
{color:green}+1 core tests.{color} The patch passed unit tests in
tajo-common tajo-core/tajo-core-backend tajo-core/tajo-core-pullserver
tajo-jdbc tajo-storage.
Test results:
https://builds.apache.org/job/PreCommit-TAJO-Build/102//testReport/
Findbugs warnings:
https://builds.apache.org/job/PreCommit-TAJO-Build/102//artifact/incubator-tajo/patchprocess/newPatchFindbugsWarningstajo-jdbc.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-TAJO-Build/102//artifact/incubator-tajo/patchprocess/newPatchFindbugsWarningstajo-storage.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-TAJO-Build/102//artifact/incubator-tajo/patchprocess/newPatchFindbugsWarningstajo-core-pullserver.html
Findbugs warnings:
https://builds.apache.org/job/PreCommit-TAJO-Build/102//artifact/incubator-tajo/patchprocess/newPatchFindbugsWarningstajo-core-backend.html
Console output: https://builds.apache.org/job/PreCommit-TAJO-Build/102//console
This message is automatically generated.
> Improve ExternalSortExec with N-merge sort and final pass omission
> ------------------------------------------------------------------
>
> Key: TAJO-36
> URL: https://issues.apache.org/jira/browse/TAJO-36
> Project: Tajo
> Issue Type: Improvement
> Components: physical operator
> Reporter: Hyunsik Choi
> Assignee: Hyunsik Choi
> Priority: Critical
> Fix For: 0.8-incubating
>
> Attachments: TAJO-36.patch, TAJO-36_140204_163419.patch,
> TAJO-36_140204_172847.patch
>
>
> Background:
> The current ExternalSortExec just uses the binary external merge sort
> algorithm
> (http://en.wikipedia.org/wiki/External_sorting#External_merge_sort). In other
> words, for each pass, ExternalSortExec just merges two files into one sorted
> file.
> Proposal:
> The goal of this proposal is to improve ExternalSortExec with the following
> improvements:
> * N-merge sort - we can merge N files though more memory at each pass. It
> will reduce the number of passes. Consequently, it will reduces considerable
> I/O overheads.
> * the final pass omission - a physical operator is pipelined by the parent
> operator. The final pass of the merge sort must also be invoked by the parent
> physical operator. So, we can omit the final pass of the merge sort.
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