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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (HIVE-74) Hive can use CombineFileInputFormat for when the input are many small files
Date Tue, 21 Apr 2009 03:43:47 GMT

    [ https://issues.apache.org/jira/browse/HIVE-74?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12701036#action_12701036
] 

dhruba borthakur edited comment on HIVE-74 at 4/20/09 8:43 PM:
---------------------------------------------------------------

This combines multiple blocks from files into a single split. All files of the same table
are part of a single pool.

      was (Author: dhruba):
    This combines multiple blocks from files into a single split.
  
> Hive can use CombineFileInputFormat for when the input are many small files
> ---------------------------------------------------------------------------
>
>                 Key: HIVE-74
>                 URL: https://issues.apache.org/jira/browse/HIVE-74
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>             Fix For: 0.4.0
>
>         Attachments: hiveCombineSplit.patch, hiveCombineSplit.patch, hiveCombineSplit2.patch
>
>
> There are cases when the input to a Hive job are thousands of small files. In this case,
there is a mapper for each file. Most of the overhead for spawning all these mappers can be
avoided if Hive used CombineFileInputFormat introduced via HADOOP-4565

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