We have physical data sources that can have many millions of rows. We are currently using Teiid's multi-source feature to union them together but, I believe Teiid is doing a proper UNION of the tables as opposed to a UNION ALL. The implied distinct operation in the UNION slows down our queries a lot because many operations cannot be pushed down to the underlying data sources and must be resolved in Teiid.

We would like the option of performing a UNION ALL on multi source models