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https://issues.apache.org/jira/browse/HIVE-17767?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vineet Garg updated HIVE-17767:
-------------------------------
    Fix Version/s: 3.0.0

> Rewrite correlated EXISTS/IN subqueries into LEFT SEMI JOIN
> -----------------------------------------------------------
>
>                 Key: HIVE-17767
>                 URL: https://issues.apache.org/jira/browse/HIVE-17767
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>            Priority: Major
>             Fix For: 3.0.0
>
>         Attachments: HIVE-17767.1.patch, HIVE-17767.2.patch, 
> HIVE-17767.3.patch, HIVE-17767.4.patch, HIVE-17767.5.patch, 
> HIVE-17767.6.patch, HIVE-17767.7.patch
>
>
> Currently such queries are written into group by + inner join with value 
> generator and is inefficient. Value generator consists of join with outer 
> query to fetch all correlated values. This value generator could be 
> completely eliminated if such queries are instead rewritten into LEFT SEMI 
> JOIN.
> Note that to do this first hive need to support LEFT SEMI JOIN with non-equi 
> condition (HIVE-17766).



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