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https://issues.apache.org/jira/browse/MAPREDUCE-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13006895#comment-13006895
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Bob Cummins commented on MAPREDUCE-2382:
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This issue is now under https://issues.apache.org/jira/browse/HBASE-3646
> Key/Value ordering within a single key/value set when multiple values exist
> for a key
> -------------------------------------------------------------------------------------
>
> 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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