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https://issues.apache.org/jira/browse/HIVE-20873?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Teddy Choi reassigned HIVE-20873:
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> 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
> Priority: Major
>
> 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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