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From "Jesus Camacho Rodriguez (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-12644) Support for offset in HiveSortMergeRule
Date Sat, 12 Dec 2015 10:43:46 GMT

    [ https://issues.apache.org/jira/browse/HIVE-12644?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15054221#comment-15054221
] 

Jesus Camacho Rodriguez commented on HIVE-12644:
------------------------------------------------

We need to check specifically for {{topOffset < (bottomOffset + bottomLimit)}}.

Observe this setting:
topOffset=1 topLimit=3
bottomOffset=1 bottomLimit=2

In this case, given the change that you propose, we would create a limit 0. However, that
is not correct. We need to create a single SortLimit operator containing:
offset=2 limit 1

> Support for offset in HiveSortMergeRule
> ---------------------------------------
>
>                 Key: HIVE-12644
>                 URL: https://issues.apache.org/jira/browse/HIVE-12644
>             Project: Hive
>          Issue Type: Bug
>          Components: CBO
>    Affects Versions: 2.1.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>         Attachments: HIVE-12644.patch
>
>
> After HIVE-11531 goes in, HiveSortMergeRule needs to be extended to support offset properly
when it merges operators that contain Limit. Otherwise, limit pushdown through outer join
optimization (introduced in HIVE-11684) will not work properly.



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