[
https://issues.apache.org/jira/browse/HIVE-20873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16678844#comment-16678844
]
slim bouguerra commented on HIVE-20873:
---------------------------------------
[~teddy.choi] Thanks, am not trying by any mean to waste your time, but it
would be nice if you share what is the improvement you see how are you
measuring it? and maybe also investigate if this will be a regression for other
queries as well.
This will help me and others to learn form your experiments.
> 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
> Labels: pull-request-available
> Attachments: HIVE-20873.1.patch, HIVE-20873.2.patch
>
>
> 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.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
