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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] [Assigned] (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 reassigned HIVE-21537:
----------------------------------
> 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
>
> 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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