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Posted to dev@hive.apache.org by "Teddy Choi (JIRA)" <ji...@apache.org> on 2018/11/06 18:00:00 UTC

[jira] [Created] (HIVE-20873) Use Murmur hash for VectorHashKeyWrapperTwoLong to reduce hash collision

Teddy Choi created HIVE-20873:
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             Summary: Use Murmur hash for VectorHashKeyWrapperTwoLong to reduce hash collision
                 Key: HIVE-20873
                 URL: https://issues.apache.org/jira/browse/HIVE-20873
             Project: Hive
          Issue Type: Improvement
            Reporter: Teddy Choi
            Assignee: Teddy Choi


VectorHashKeyWrapperTwoLong is implemented with few bit shift operators and XOR operators for short computation time, but more hash collision. Group by operations become very slow on large data sets. It needs Murmur hash or a better hash function for less hash collision.



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