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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Updated: (PIG-196) Pig should use '-reducer NONE' for map-only jobs
Date Sat, 12 Apr 2008 23:50:04 GMT

     [ https://issues.apache.org/jira/browse/PIG-196?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Arun C Murthy updated PIG-196:

    Status: Patch Available  (was: Open)

Passes tests locally... I'm hoping the change to file names is acceptable.

> Pig should use '-reducer NONE' for map-only jobs
> ------------------------------------------------
>                 Key: PIG-196
>                 URL: https://issues.apache.org/jira/browse/PIG-196
>             Project: Pig
>          Issue Type: Bug
>            Reporter: Arun C Murthy
>            Assignee: Arun C Murthy
>         Attachments: PIG-196_0_20080412.patch
> Currently, for map-only jobs, Pig writes map-outputs directly to HDFS and then sends
zero data to reducers. The problem with this is two fold:
>  * Reduce slots are unnecessarily wasted on the cluster
>  * Reduces write empty files to HDFS putting pressure on the Namenode
> Both these can we very easily avoided by just calling:
> {noformat}
> job.setNumReduces(0);
> {noformat}
> and letting Hadoop Map-Reduce take care of writing map-outputs directly to HDFS.

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