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From "Tom White (JIRA)" <j...@apache.org>
Subject [jira] Updated: (MAPREDUCE-1489) DataDrivenDBInputFormat should not query the database when generating only one split
Date Fri, 26 Mar 2010 23:51:27 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-1489?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Tom White updated MAPREDUCE-1489:
---------------------------------

       Resolution: Fixed
    Fix Version/s: 0.22.0
     Hadoop Flags: [Reviewed]
           Status: Resolved  (was: Patch Available)

+1 I've just committed this. Thanks Aaron!

> DataDrivenDBInputFormat should not query the database when generating only one split
> ------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1489
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1489
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: contrib/sqoop
>            Reporter: Aaron Kimball
>            Assignee: Aaron Kimball
>             Fix For: 0.22.0
>
>         Attachments: MAPREDUCE-1489.patch
>
>
> DataDrivenDBInputFormat runs a query to establish bounding values for each split it generates;
but if it's going to generate only one split (mapreduce.job.maps == 1), then there's no reason
to do this. This will remove overhead associated with a single-threaded import of a non-indexed
table since it avoids a full table scan.

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