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Posted to dev@hive.apache.org by "Gopal V (JIRA)" <ji...@apache.org> on 2014/05/23 23:35:01 UTC

[jira] [Created] (HIVE-7121) Use murmur hash to distribute HiveKey

Gopal V created HIVE-7121:
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             Summary: Use murmur hash to distribute HiveKey
                 Key: HIVE-7121
                 URL: https://issues.apache.org/jira/browse/HIVE-7121
             Project: Hive
          Issue Type: Bug
          Components: Query Processor
            Reporter: Gopal V
            Assignee: Gopal V


The current hashCode implementation produces poor parallelism when dealing with single integers or doubles.

And for partitioned inserts into a 1 bucket table, there is a significant hotspot on Reducer #31.

Removing the magic number 31 and using a more normal hash algorithm would help fix these hotspots.



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