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From "Mayank Lahiri (JIRA)" <j...@apache.org>
Subject [jira] Created: (HIVE-1372) New algorithm for variance() UDAF
Date Wed, 26 May 2010 21:51:36 GMT
New algorithm for variance() UDAF
---------------------------------

                 Key: HIVE-1372
                 URL: https://issues.apache.org/jira/browse/HIVE-1372
             Project: Hadoop Hive
          Issue Type: Improvement
          Components: Query Processor
    Affects Versions: 0.6.0
            Reporter: Mayank Lahiri
            Priority: Minor
             Fix For: 0.6.0


A new algorithm for the UDAF that computes variance. This is pretty much a drop-in replacement
for the current UDAF, and has two benefits: provably numerically stable (reference included
in comments), and reduces arithmetic operations by about half.

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