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Posted to mapreduce-issues@hadoop.apache.org by "Alejandro Abdelnur (JIRA)" <ji...@apache.org> on 2012/12/19 04:36:12 UTC

[jira] [Commented] (MAPREDUCE-4891) Pluggable merge at reduce side

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13535618#comment-13535618 ] 

Alejandro Abdelnur commented on MAPREDUCE-4891:
-----------------------------------------------

Jerry, unless I'm missing something from your description, this is a duplicate of MAPREDUCE-4808. Would you please check if that is the case and close this this one as dup of MAPREDUCE-4808 is so?. Thx
                
> Pluggable merge at reduce side
> ------------------------------
>
>                 Key: MAPREDUCE-4891
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4891
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>    Affects Versions: 3.0.0
>            Reporter: Jerry Chen
>   Original Estimate: 504h
>  Remaining Estimate: 504h
>
> The current implementation of sort in MapReduce is cooperated by Map side sort and Reduce side merge.  MAPREDUCE-2454 provided pluggable sort at the Map side currently and pluggable shuffle at Reduce side, while no pluggable merger provided.
> Considering a general need of hash grouping and join, we may need to replace both the Map Sort and Reduce merge with a more light weight hash grouping alorithm. A general pluggable merge would help support this need.

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