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From "Rahul Sharma (JIRA)" <>
Subject [jira] [Commented] (CRUNCH-51) PCollection#sort relies on using a single reducer for total order sorting
Date Wed, 19 Sep 2012 12:38:08 GMT


Rahul Sharma commented on CRUNCH-51:

I just realized that it is a log statement that I wrote back in Sort function. Actually we
need to create file only when the number of reducers is greater than 1. So that's number corresponds
to the no of keys in partition file, if it is greater than1 then we create it. I think we
can improve the log statement.
I tested it with string data and avro data for ascending and descending order.It worked fine.
Please have a go at it if it still gives issues. 
> PCollection#sort relies on using a single reducer for total order sorting
> -------------------------------------------------------------------------
>                 Key: CRUNCH-51
>                 URL:
>             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,
> 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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