[jira] Updated: (HADOOP-3019) want input sampler & sorted partitioner

["Robert Chansler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-3019?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Chansler updated HADOOP-3019:
------------------------------------

    Release Note: Added a partitioner that effects a total order of output data, and an input sampler for generating the partition keyset for TotalOrderPartitioner for when the map's input keytype and distribution approximates its output.  (was: Adds a partitioner capable of effecting a total order of output data. Also includes an input sampler for generating the partition keyset for TotalOrderPartitioner, useful where the map's input keytype and distribution approximates its output.)

> want input sampler & sorted partitioner
> ---------------------------------------
>
>                 Key: HADOOP-3019
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3019
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: mapred
>            Reporter: Doug Cutting
>            Assignee: Chris Douglas
>             Fix For: 0.19.0
>
>         Attachments: 3019-0.patch, 3019-1.patch, 3019-2.patch, 3019-3.patch, 3019-4.patch, 3019-5.patch
>
>
> The input sampler should generate a small, random sample of the input, saved to a file.
> The partitioner should read the sample file and partition keys into relatively even-sized key-ranges, where the partition numbers correspond to key order.
> Note that when the sampler is used for partitioning, the number of samples required is proportional to the number of reduce partitions.  10x the intended reducer count should give good results.

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