Julian Hyde created OPTIQ-330:
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Summary: Add a rule that converts join-on-aggregate to semi-join
Key: OPTIQ-330
URL: https://issues.apache.org/jira/browse/OPTIQ-330
Project: Optiq
Issue Type: New Feature
Reporter: Julian Hyde
Assignee: Julian Hyde
Once OPTIQ-328 is completed and JoinRelBase has a flag
eliminateRightDuplicates, we need a rule to populate that flag from SQL queries.
Transformers that deal with 'IN subquery' (both correlated and uncorrelated)
should set this flag. (In particular check TPC-DS Q95.)
Also queries written '... JOIN (SELECT DISTINCT ...)'.
Also handle queries whose right input is known to be already unique, e.g.
{code:sql}
SELECT emp.name
FROM emp JOIN dept USING (deptno)
WHERE dept.location = 'San Francisco'
{code}
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