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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3308) Improve QuickSort by excluding values eq the pivot from the partition
Date Thu, 24 Apr 2008 20:47:27 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-3308?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Chris Douglas updated HADOOP-3308:
----------------------------------

    Assignee: Chris Douglas
      Status: Patch Available  (was: Open)

> 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
>
>
> 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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