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

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

Vineet Garg created HIVE-21537:
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             Summary: 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


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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