[jira] [Created] (HIVE-18008) Add optimization rule to remove gby from right side of left semi-join

["Vineet Garg (JIRA)" <ji...@apache.org>]

Vineet Garg created HIVE-18008:
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             Summary: 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


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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