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https://issues.apache.org/jira/browse/HIVE-7121?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gopal V updated HIVE-7121:
--------------------------
Attachment: HIVE-7121.2.patch
Fix the table bucketed insert case by limiting the murmur hash to cases with
variable number of reducers.
This neatly avoids using the new hash function where there are explicit bucket
counts or reducer counts.
> 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.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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