I'd like to do something like that too, if/when I ever get to replacing the DDL. In Postgres you could create custom types for tagged unions, but it might be be

I'd like to do something like that too, if/when I ever get to replacing the DDL. In Postgres you could create custom types for tagged unions, but it might be better to translate table-level unions to a set of constraints, for performance and flexibility (you can't create referential integrity constraints using expressions IIRC).