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From "nicu marasoiu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-5287) Create a generic InputFormat wrapping any other InputFormat, to control the number of map tasks
Date Fri, 31 May 2013 12:12:19 GMT
nicu marasoiu created MAPREDUCE-5287:
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             Summary: Create a generic InputFormat wrapping any other InputFormat, to control
the number of map tasks
                 Key: MAPREDUCE-5287
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5287
             Project: Hadoop Map/Reduce
          Issue Type: Improvement
          Components: mrv1, performance
            Reporter: nicu marasoiu


I wrote a generic InputFormat that wraps any other InputFormat, and creates CompositeInputSplits
to reduce the number of map tasks in a controllable manner while preserving data locality.
A correspondent CompositeRecordReader is written to iterate through underlying RecordReaders
as created by the underlying InputFormat for each underlying raw split.

An application to this is to group TableSplits when the raw splits are coming from multiple
regions and are filtered with key ranges. We use this to shard/distribute a time based incremental
access to an hbase table.

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