[teiid-issues] [JBoss JIRA] (TEIID-1991) GROUP BY pushdown into subselect of UNIONs

GROUP BY pushdown into subselect of UNIONs ------------------------------------------ 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: 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