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Posted to issues@hbase.apache.org by "Jesse Yates (JIRA)" <ji...@apache.org> on 2011/09/16 21:10:09 UTC

[jira] [Commented] (HBASE-3646) When mapper writes multiple values for a key keep chronological order of values

    [ https://issues.apache.org/jira/browse/HBASE-3646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13106724#comment-13106724 ] 

Jesse Yates commented on HBASE-3646:
------------------------------------

@Bob How is this patch coming along? If you guys have dropped it, I would be interested in taking a stab at it.

@stack Is this ticket even still valid? Should we bump the version number?

Thanks!

> 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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