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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-1473) Implement a Cassandra aware Hadoop mapreduce.Partitioner
Date Thu, 11 Aug 2011 13:59:27 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1473?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13083120#comment-13083120
] 

Jonathan Ellis commented on CASSANDRA-1473:
-------------------------------------------

That is, I don't think we can do this for non-RP Cassandra partitioner.

I guess it's still worth doing since RP is the recommended.  Should we return 0, or random(0..numPartitions)
for BOP?

Also not sure how you go about registering your custom mr.Partitioner w/ Hadoop.

> Implement a Cassandra aware Hadoop mapreduce.Partitioner
> --------------------------------------------------------
>
>                 Key: CASSANDRA-1473
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1473
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Hadoop
>            Reporter: Stu Hood
>            Assignee: Patricio Echague
>             Fix For: 1.0
>
>
> When using a IPartitioner that does not sort data in byte order (RandomPartitioner for
example) with Cassandra's Hadoop integration, Hadoop is unaware of the output order of the
data.
> We can make Hadoop aware of the proper order of the output data by implementing Hadoop's
mapreduce.Partitioner interface: then Hadoop will handle sorting all of the data according
to Cassandra's IPartitioner, and the writing clients will be able to connect to smaller numbers
of Cassandra nodes.

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