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From "Cummins, Robert [USA]" <cummins_rob...@bah.com>
Subject mapreduce passed parameter value ordering
Date Tue, 22 Feb 2011 15:45:53 GMT
Is the following acceptable or is an enhancement/bug fix needed?


For mapper class:


       class Mapper1 extends TableMapper<ImmutableBytesWritable,


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. 



Suggestion: It would be a helpful and simple feature to have chronological
order guaranteed as a facility for identification by the reducer.





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