hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Alejandro Abdelnur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3702) add support for chaining Maps in a single Map and after a Reduce [M*/RM*]
Date Tue, 05 Aug 2008 11:12:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12619844#action_12619844
] 

Alejandro Abdelnur commented on HADOOP-3702:
--------------------------------------------

*On #1*, I don't have a problem either way, I was just trying to be as less disruptive as
possible. Somebody has to make the call here.

*On #2*, I've tried to generify {{ChainOutputCollector}} but hitting a wall there, I never
have the types to instantiate it so I keep getting the compiler warnings. Thoughts?


> 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
>         Attachments: patch3702.txt, patch3702.txt, patch3702.txt, patch3702.txt, patch3702.txt,
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.


Mime
View raw message