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https://issues.apache.org/jira/browse/MAPREDUCE-4808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13554536#comment-13554536
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Arun C Murthy commented on MAPREDUCE-4808:
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I'll admit I'm really confused - the jira says 'make reduce-side merge
pluggable' and then the patch does changes to MapOutput, tries to make
MergeManager a resolver etc.
OTOH, there is a concrete alternative to introduce a Merger abstraction which
solves the use-cases described i.e. limit-N, hash-join etc.
Why are we not doing the straight-fwd thing of solving what the jira intends to
do i.e. make merge pluggable?
Are we trying to solve something else here? If so, can we at least articulate
what we are trying to solve? Thanks.
> Allow reduce-side merge to be pluggable
> ---------------------------------------
>
> Key: MAPREDUCE-4808
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4808
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Affects Versions: 2.0.2-alpha
> Reporter: Arun C Murthy
> Assignee: Mariappan Asokan
> Fix For: 2.0.3-alpha
>
> Attachments: COMBO-mapreduce-4809-4812-4808.patch,
> mapreduce-4808.patch, mapreduce-4808.patch, mapreduce-4808.patch,
> mapreduce-4808.patch, mapreduce-4808.patch, mapreduce-4808.patch,
> mapreduce-4808.patch, MergeManagerPlugin.pdf
>
>
> Allow reduce-side merge to be pluggable for MAPREDUCE-2454
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