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https://issues.apache.org/jira/browse/HADOOP-3308?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HADOOP-3308:
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    Hadoop Flags: [Reviewed]

> Improve QuickSort by excluding values eq the pivot from the partition
> ---------------------------------------------------------------------
>
>                 Key: HADOOP-3308
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3308
>             Project: Hadoop Core
>          Issue Type: Improvement
>            Reporter: Chris Douglas
>            Assignee: Chris Douglas
>             Fix For: 0.18.0
>
>         Attachments: 3308-0.patch, 3308-1.patch, 3308-2.patch
>
>
> The current implementation of QuickSort naively partitions on either side of 
> the pivot. We can improve this by partitioning on either side of the set of 
> values equal to the pivot. This assumes that comparing keys is expensive 
> compared to swaps and index comparisons (which it certainly is in MapTask, 
> and should be in general).

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