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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-3308) Improve QuickSort by excluding values eq the pivot from the partition
Date Thu, 24 Apr 2008 20:45:21 GMT
Improve QuickSort by excluding values eq the pivot from the partition
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                 Key: HADOOP-3308
                 URL: https://issues.apache.org/jira/browse/HADOOP-3308
             Project: Hadoop Core
          Issue Type: Improvement
            Reporter: Chris Douglas
             Fix For: 0.18.0


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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