Bug 242813 has been fixed now so homogeneous unions should be fine now.
It is probably still worth tweaking the expression compiler so that the SQL we generate for other cases is more likely to pass MySQL's finicky parser.
Bug 242813 has been fixed now so homogeneous unions should be fine now.
It is probably still worth tweaking the expression compiler so that the SQL we generate for other cases is more likely to pass MySQL's finicky parser.