Key/Value ordering within a single key/value set when multiple values exist for
a key
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Key: MAPREDUCE-2382
URL: https://issues.apache.org/jira/browse/MAPREDUCE-2382
Project: Hadoop Map/Reduce
Issue Type: Improvement
Components: client
Affects Versions: 0.20.2
Reporter: Bob Cummins
Priority: Minor
>>The context of this issue is entirely within one key/value(s) pair/set, NOT
>>between key/value sets as they are funneled to a reducer by mappers.<<
When mapper writes multiple values for a key, the underlying collection class
maps each of the values to the key, but not always in chronological order. If
chronological order were guaranteed each of the values mapped to the key, each
of the values could be understood as specific and different parameters between
the mapper and the reducer.
I've done little tricks like having the mapper flag one a the values by making
it a negative number, which the reducer recognizes and can write it to hbase
as a unique column value.This is a kluge workaround which it would be nice to
not have to do.
Used to formulate this suggestion:
TableMapper<ImmutableBytesWritable,IntWritable>
TableReducer<ImmutableBytesWritable,IntWritable, ImmutableBytesWritable>
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