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Posted to issues@hive.apache.org by "Vineet Garg (JIRA)" <ji...@apache.org> on 2019/03/28 22:37:00 UTC

[jira] [Updated] (HIVE-21537) Scalar query rewrite could be improved to not generate an extra join if subquery is guaranteed to produce atmost one row

     [ https://issues.apache.org/jira/browse/HIVE-21537?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vineet Garg updated HIVE-21537:
-------------------------------
    Labels: sub-query  (was: )

> Scalar query rewrite could be improved to not generate an extra join if subquery is guaranteed to produce atmost one row
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-21537
>                 URL: https://issues.apache.org/jira/browse/HIVE-21537
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>    Affects Versions: 4.0.0
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>            Priority: Major
>              Labels: sub-query
>
> Currently Hive planner introduces this branch and later executes a rule to remove this branch if it could. 
> Subquery remove rule itself could check if subquery will produce max one row (using relmetadat's getMaxRowCount) and avoid introducing this branch.



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