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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-987) We need a Hbase Partitioner for TableMapReduceUtil.initTableReduceJob MR Jobs
Date Mon, 10 Nov 2008 23:59:44 GMT

    [ https://issues.apache.org/jira/browse/HBASE-987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12646415#action_12646415

stack commented on HBASE-987:

Rather than enum, just have an override for TMRU.initTableReduceJob that takes a Partitioner.
 Default is use the old Partitioner?

If you do the above, I'll do the bit that adds documentation on this new facility?

> We need a Hbase Partitioner for TableMapReduceUtil.initTableReduceJob MR Jobs
> -----------------------------------------------------------------------------
>                 Key: HBASE-987
>                 URL: https://issues.apache.org/jira/browse/HBASE-987
>             Project: Hadoop HBase
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Billy Pearson
>            Assignee: Billy Pearson
>            Priority: Minor
>             Fix For: 0.19.0
>         Attachments: 987-2.patch.txt, 987.patch.txt
> When we run say 20 reducers they all get ~1/20th of the data to output to the table.
> The problem for us on large import jobs is the data gets sorted by key and the all Reducers

> pound one region at a time.
> we need to add onto the TableMapReduceUtil.initTableReduceJob method so it can set the
> and set the number of reducers = number of regions as the table map does for maps.
> Then the Partitioner will send all the BatchUpdates for one region to one reducer.
> So we get a more even spread of writers to the regions this would assure that only one
reducer will send 
> updates to one region keeping any one region from getting more overloaded the others.

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