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https://issues.apache.org/jira/browse/HIVE-18008?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vineet Garg updated HIVE-18008:
-------------------------------
    Fix Version/s: 3.0.0

> Add optimization rule to remove gby from right side of left semi-join
> ---------------------------------------------------------------------
>
>                 Key: HIVE-18008
>                 URL: https://issues.apache.org/jira/browse/HIVE-18008
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>            Priority: Major
>             Fix For: 3.0.0
>
>         Attachments: HIVE-18008.1.patch, HIVE-18008.2.patch
>
>
> Group by (on same keys as semi join) as right side of Left semi join is 
> unnecessary and could be removed. We see this pattern in subqueries with 
> explicit distinct keyword e.g.
> {code:sql}
> explain select * from src b where b.key in (select distinct key from src a 
> where a.value = b.value)
> {code}



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