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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3019) want input sampler & sorted partitioner
Date Wed, 17 Sep 2008 00:03:44 GMT

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

Chris Douglas updated HADOOP-3019:
----------------------------------

    Attachment: 3019-2.patch

Changed random sampling to be less dominated by keys in the latter part of each sampled split.

> 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
>
>
> 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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