jpql - JPA only executes first select statement in union?

Question

I've written a JPQL statement that unions multiple select statements, each of which selects a different string constant. A simplified version of the query would look something like this:

SELECT DISTINCT 'A' AS widget_type
  FROM WidgetA widgetA
  WHERE widgetA.creationTimestamp > :cutoff
UNION SELECT DISTINCT 'B' AS widget_type
  FROM WidgetB widgetB
  WHERE widgetB.creationTimestamp > :cutoff

The query doesn't cause any errors but I'm not getting the result I expect. I see that the generated SQL doesn't have any unions - it only queries the table from the first select:

select distinct 'A' as col_0_0_ 
from widget_a widget0_
where widget0_.creation_timestamp>?

Is there an obvious reason why JPA would disregard everything after the first select statement? If it makes any difference, I am using Hibernate 4.1.9 as the JPA implementation, with a MySQL database.

Answer 1

JPQL has no such concept as UNION. So consequently any "query" that has it is not JPQL and so ought to be rejected as invalid JPQL (which DataNucleus JPA certainly would do)