string_agg should return null rather than empty over no values -------------------------------------------------------------- Key: TEIID-5471 URL: https://issues.jboss.org/browse/TEIID-5471 Project: Teiid Issue Type: Bug Components: Query Engine Reporter: Steven Hawkins Assignee: Steven Hawkins Fix For: 11.2 For example the query: select string_agg(col, ',') from (select cast(null as string) as col) x Should return null rather than an empty string.