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From "Namit Jain (JIRA)" <>
Subject [jira] Commented: (HIVE-439) merge small files whenever possible
Date Tue, 09 Jun 2009 21:09:07 GMT


Namit Jain commented on HIVE-439:

Instead of having a map-only job to do the concatenation, I think we should use a map-reduce
This way, when sorting properties of a table are maintained in the metastore, they can be

> merge small files whenever possible
> -----------------------------------
>                 Key: HIVE-439
>                 URL:
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Namit Jain
>            Assignee: Namit Jain
> 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 these small files are combined into fewer larger files.
> The problem can also be addressed by having a mapper span multiple blocks as in:
> Bit, it also makes sense in HIVE to merge files whenever possible.

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