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From "Gabriel Reid (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-51) PCollection#sort relies on using a single reducer for total order sorting
Date Fri, 22 Mar 2013 16:07:16 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-51?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13610426#comment-13610426
] 

Gabriel Reid commented on CRUNCH-51:
------------------------------------

Yep, I'll try to get a good look at this this weekend -- I'll try to find the test cases that
I was using to test some of this stuff out in the past.

For now, I just took a quick skim through the patch and noticed one small nit-pick -- the
license header in SortExample.java is a Cloudera license header instead of the standard Apache
license header.


                
> PCollection#sort relies on using a single reducer for total order sorting
> -------------------------------------------------------------------------
>
>                 Key: CRUNCH-51
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-51
>             Project: Crunch
>          Issue Type: Improvement
>    Affects Versions: 0.3.0
>            Reporter: Gabriel Reid
>         Attachments: 0001-CRUNCH-51-Total-Order-Sort.patch, CRUNCH-51.patch, CRUNCH-51.patch,
CRUNCH-51.patch, CRUNCH-51-ready.patch, SortTest.java
>
>
> The total-order sorting provided by the Sort class (and therefore PCollection#sort) relies
on using a single reducer in order to provide total-order sorting. This is very inefficient
for large datasets, and should be replaced with a total order partitioner instead.
> For more information, see CRUNCH-23 (and possibly also MAPREDUCE-4574).

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