[
https://issues.apache.org/jira/browse/HADOOP-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Alejandro Abdelnur updated HADOOP-3702:
---------------------------------------
Release Note:
The ChainMapper and the ChainReducer classes allow composing chains of Maps and
Reduces in a single Map/Reduce job, something like MAP+ / REDUCE MAP*. An
immediate benefit of this pattern is reduction in disk IO as many Maps can be
club together in a single job.
was:
The ChainMapper and the ChainReducer classes allow composing chains of Maps and
Reduces in a single Map/Reduce job, something like MAP+ / REDUCE MAP*.
An immediate benefit of this pattern is reduction in disk IO as many Maps can
be club together in a single job.
Status: Patch Available (was: Open)
> add support for chaining Maps in a single Map and after a Reduce [M*/RM*]
> -------------------------------------------------------------------------
>
> Key: HADOOP-3702
> URL: https://issues.apache.org/jira/browse/HADOOP-3702
> Project: Hadoop Core
> Issue Type: New Feature
> Components: mapred
> Environment: all
> Reporter: Alejandro Abdelnur
> Assignee: Alejandro Abdelnur
> Priority: Minor
> Attachments: patch3702.txt, patch3702.txt, patch3702.txt,
> patch3702.txt, patch3702.txt
>
>
> On the same input, we usually need to run multiple Maps one after the other
> without no Reduce. We also have to run multiple Maps after the Reduce.
> If all pre-Reduce Maps are chained together and run as a single Map a
> significant amount of Disk I/O will be avoided.
> Similarly all post-Reduce Maps can be chained together and run in the Reduce
> phase after the Reduce.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
