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From "Shreepadma Venugopalan" <shreepa...@cloudera.com>
Subject Review Request: HIVE-4435: Column stats: Distinct value estimator should use hash functions that are pairwise independent
Date Mon, 29 Apr 2013 20:41:27 GMT

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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/10841/
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Review request for hive.


Description
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Fixes the FM estimator to use hash functions that are pairwise independent.


This addresses bug HIVE-4435.
    https://issues.apache.org/jira/browse/HIVE-4435


Diffs
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  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/NumDistinctValueEstimator.java 69e6f46


Diff: https://reviews.apache.org/r/10841/diff/


Testing
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The estimates are within the expected error after this fix. Tested on TPCH of varying sizes.


Thanks,

Shreepadma Venugopalan


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