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From "Aaron Kimball (JIRA)" <j...@apache.org>
Subject [jira] Updated: (MAPREDUCE-1489) DataDrivenDBInputFormat should not query the database when generating only one split
Date Sat, 13 Feb 2010 01:47:27 GMT

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

Aaron Kimball updated MAPREDUCE-1489:
-------------------------------------

    Attachment: MAPREDUCE-1489.patch

Attaching patch which improves DataDrivenDBInputFormat in this manner. Also updated use of
deprecated config keys nearby.

The majority of tests for DDDBIF are implicit in the Sqoop tests; I've modified these so that
some Sqoop tests respect the old code-path by requesting multiple map tasks, but other Sqoop
tests will use a single task.

This patch is based on the code in MAPREDUCE-1460; will mark as patch-available when that's
committed.

> 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
>         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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