[teiid-issues] [JBoss JIRA] (TEIID-3696) Duplicates are not always removed when UNION and GROUP BY clauses are used in a subquery

Duplicates are not always removed when UNION and GROUP BY clauses are used in a subquery ---------------------------------------------------------------------------------------- Key: TEIID-3696 URL: https://issues.jboss.org/browse/TEIID-3696 Project: Teiid Issue Type: Bug Components: Query Engine Affects Versions: 8.1 Reporter: Salvatore R Assignee: Steven Hawkins Priority: Blocker Fix For: 8.12, 8.11.4, 8.7.5, 8.7.6.6_2 In some cases, duplicates are not correctly removed when a UNION clause and a GROUP BY are used in a subquery. Given, for example, these two views: {code:sql} CREATE view v1 as select 'a' as col1 UNION SELECT '' as col1; CREATE view v2 as select 'b' as col1 UNION SELECT '' as col1; {code} running the following query (both col1 and col2 are projected by the main query): {code:sql} select y.col2, y.col1 from ( select x.col2, min(x.col1) as col1 from ( select 1 as col2, col1 from "views.v1" union select 1 as col2, col1 from "views.v2" ) x group by x.col2 ) y {code} only 1 row is returned as expected: ||col2||col1|| |1| | but if only "col2" is projected by the main query: {code:sql} select y.col2 from ( select x.col2, min(x.col1) as col1 from ( select 1 as col2, col1 from "views.v1" union select 1 as col2, col1 from "views.v2" ) x group by x.col2 ) y {code} three rows are returned: ||col2|| |1| |1| |1| This behavior can be reproduced in Teiid-8.12-Beta1.