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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-3646) When mapper writes multiple values for a key keep chronological order of values
Date Thu, 04 Oct 2012 21:09:48 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13469703#comment-13469703

Lars Hofhansl commented on HBASE-3646:

Any update on this?
> When mapper writes multiple values for a key keep chronological order of values
> -------------------------------------------------------------------------------
>                 Key: HBASE-3646
>                 URL: https://issues.apache.org/jira/browse/HBASE-3646
>             Project: HBase
>          Issue Type: New Feature
>          Components: Client
>    Affects Versions: 0.90.1
>         Environment: Cloudera 3.5 VM 
> TableMapper<ImmutableBytesWritable,IntWritable>
> TableReducer<ImmutableBytesWritable,IntWritable, ImmutableBytesWritable>
>            Reporter: Bob Cummins
>            Priority: Minor
> 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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