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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