[teiid-issues] [JBoss JIRA] (TEIID-1991) GROUP BY pushdown into subselect of UNIONs
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https://issues.jboss.org/browse/TEIID-1991?page=com.atlassian.jira.plugin...
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Mark Addleman commented on TEIID-1991:
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That did it! Thanks.
For future readers, my original query should be stated as
SELECT t.a FROM (
SELECT n.name, dm1.a FROM dm1, (SELECT 'abc' AS name) n WHERE
n.name='abc'
UNION ALL
SELECT n.name, dm2.a FROM dm2, (SELECT 'xyz' AS name) n WHERE
n.name='xyz'
) t
GROUP BY pushdown into subselect of UNIONs
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Key: TEIID-1991
URL: https://issues.jboss.org/browse/TEIID-1991
Project: Teiid
Issue Type: Bug
Components: Query Engine
Affects Versions: 7.7
Reporter: Mark Addleman
Assignee: Steven Hawkins
Attachments: efficient_rewrite.txt, plan.txt, plan.txt, simplified_plan.txt
If have a query of the form
SELECT a FROM (
SELECT a FROM (
SELECT a FROM ds.t1
) u
) t GROUP BY a
Teiid correctly optimizes the inner SELECT to SELECT 1 FROM ds.t1. However, if the inner
subselect is a union:
SELECT a FROM (
SELECT a FROM (
SELECT a FROM ds.t1 UNION
SELECT a FROM ds.t2
) u
) t GROUP BY a
Teiid does not optimize to
SELECT 1 FROM ds.t1 UNION
SELECT 1 FROM ds.t2
as I would expect.
See attached plan
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