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From "Bob Cummins (JIRA)" <j...@apache.org>
Subject [jira] Created: (MAPREDUCE-2369) Using TableMapper Iterable IntWritables not passed to the reducer in order put by mapper
Date Tue, 08 Mar 2011 13:32:59 GMT
Using TableMapper Iterable IntWritables not passed to the reducer in order put by mapper
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                 Key: MAPREDUCE-2369
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2369
             Project: Hadoop Map/Reduce
          Issue Type: Improvement
          Components: client
    Affects Versions: 0.20.2
         Environment: Cloudera VM 3.5
            Reporter: Bob Cummins
            Priority: Minor


For mapper class:
      class Mapper1 extends TableMapper<ImmutableBytesWritable,IntWritable>
With reducer class:
     class Reducer1 extends TableReducer<ImmutableBytesWritable,IntWritable, ImmutableBytesWritable>

Iterable<IntWritable> values are usually received by the reducer in the
order the values are written to the context by the mapper. However in my
testing about 5% of cases, the same order is not maintained, and the ability
of the reducer to categorize a value by order lost.
Chronological order guaranteed would serve as a facility for identification by the reducer.

 

 

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