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From "Dave Beech (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-162) Add utility function for merging output by identity reduce
Date Wed, 06 Feb 2013 10:31:12 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572313#comment-13572313
] 

Dave Beech commented on CRUNCH-162:
-----------------------------------

I've got a patch for this but I've just realised the code is almost identical to something
in the Sort class (or at least, how it was before the hardcoded single reducer from CRUNCH-23).
The "sort-pre" function followed by the GBK and ungroup is what I need, but with configurable
numbers of reducers rather than configurable sort order. Also I've just noticed that the "sort-post"
function inside Sort is a duplicate of PTables.keys

I don't want to add any further duplication. Any ideas?

 


                
> Add utility function for merging output by identity reduce
> ----------------------------------------------------------
>
>                 Key: CRUNCH-162
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-162
>             Project: Crunch
>          Issue Type: Improvement
>          Components: MapReduce Patterns
>    Affects Versions: 0.4.0
>            Reporter: Dave Beech
>            Priority: Minor
>
> Something I find myself doing reasonably often in mapreduce is to use
> the reduce step as nothing more than a means to merge data into larger
> files (using the identity reducer). 
> There doesn't appear to be a neat way to do this with Crunch at the moment.
> Ref: http://mail-archives.apache.org/mod_mbox/incubator-crunch-user/201302.mbox/%3CCAFZSZPsXRxWT45c9w4ef7Ruij2exE4HP2CDNMjd%2BVc%3D9RWX-Jw%40mail.gmail.com%3E

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