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https://issues.apache.org/jira/browse/HADOOP-3387?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12597202#action_12597202
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Owen O'Malley commented on HADOOP-3387:
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If there are deficiencies, please work to fix the current implementation.
Having N instances of each input format isn't very useful.
1. If you ask for 10 maps and there are 5 files and it generates 5 maps, I
don't understand how the planner was supposed to know that you really wanted
one.
2.If you ask for 3 maps, I don't understand why you are upset that it allocated
3 maps.
Your goals don't seem to be well defined.
> Custom Splitter for handling many small files
> ---------------------------------------------
>
> Key: HADOOP-3387
> URL: https://issues.apache.org/jira/browse/HADOOP-3387
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Subramaniam Krishnan
> Assignee: Subramaniam Krishnan
> Fix For: 0.18.0
>
>
> Hadoop by default allocates a Map to a file irrespective of size. This is not
> optimal if you have a large number of small files, for e.g:- If you 2000
> 100KB files, 2000 Maps will be allocated for the job.
> The Custom Multi File Splitter collapses all the small files to a single
> split till the DFS Block Size is hit.
> It also take care of handling big files by splitting them on Block Size and
> adding up all the reminders(if any) to a further splits of Block Size.
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