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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