I'm confused, how do you design a database where things in A can't reference things in B? It's not relational at that point right? Or is this just about the pr

I'm confused, how do you design a database where things in A can't reference things in B? It's not relational at that point right? Or is this just about the problems of DBs where you enforce referential integrity? In which case, if that's such a problem, like just don't enforce referential integrity...right?