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From "Gunther Hagleitner (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-7121) Use murmur hash to distribute HiveKey
Date Fri, 30 May 2014 04:48:02 GMT

     [ https://issues.apache.org/jira/browse/HIVE-7121?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gunther Hagleitner updated HIVE-7121:
-------------------------------------

    Status: Patch Available  (was: Open)

> 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
>         Attachments: HIVE-7121.1.patch, HIVE-7121.2.patch, HIVE-7121.3.patch, HIVE-7121.WIP.patch
>
>
> 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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