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https://issues.apache.org/jira/browse/CASSANDRA-1473?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13083117#comment-13083117
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Jonathan Ellis commented on CASSANDRA-1473:
-------------------------------------------
{noformat}
/** Get the partition number for a given key (hence record) given the total
number of partitions */
getPartition(KEY key, VALUE value, int numPartitions)
*/
{noformat}
I don't think we can do this, without knowing the total number of keys as well.
:(
> 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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