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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-19578) HLL merges tempList on every add
Date Thu, 17 May 2018 07:55:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-19578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16478696#comment-16478696
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Prasanth Jayachandran commented on HIVE-19578:
----------------------------------------------

Int2ByteSortedMap is in fastutil. This dependency is 18MB jar. I am not sure if it be worth
it to bring such a big dependency as this jar also has to be bundled with hive-exec. We discussed
this during the initial HLL implementation that this 3rd party dependency is big and replaced
Int2ByteSortedMap with java TreeMap. If performance becomes a bigger concern we can consider
bringing the jar, I think for now we can stick on to TreeMap and add just the optimizations. 

 

> HLL merges tempList on every add
> --------------------------------
>
>                 Key: HIVE-19578
>                 URL: https://issues.apache.org/jira/browse/HIVE-19578
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Sergey Shelukhin
>            Assignee: Prasanth Jayachandran
>            Priority: Major
>         Attachments: Screen Shot 2018-05-16 at 15.29.12 .png
>
>
>  See comments on HIVE-18866; this has significant perf overhead after the even bigger
overhead from hashing is removed.  !Screen Shot 2018-05-16 at 15.29.12 .png!



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