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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