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Posted to mapreduce-issues@hadoop.apache.org by "Jerry Chen (JIRA)" <ji...@apache.org> on 2012/12/19 04:06:12 UTC

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

Jerry Chen created MAPREDUCE-4891:
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             Summary: 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


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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