so we would not need to get a full Union every time when checking changes in data when you already know you have cheked those unions in some day before? in Profile api it is already there and it is helping a lot. updated_at should change when union has changes, example added/removed/changed childs/parents.. that would lower the server load a lot when you just check union's updated_at and let the datacheckingroutines leave it if it is already checked and nothing has changed.
