I was just listening to the 2 Matts on FileMaker Talk, and they were discussing the validation options when you define a field. The gist of the conversation was that these are mostly unnecessary and more trouble than they're worth. They even disparaged the "unique" validation because of its impact on performance. But the "unique" validation is valuable and necessary when defining any field that acts as a primary key, right? I've never tried creating a primary key without using "unique" validation. All I know is that the relationship graph will not denote a one-to-many relationship unless one of the fields is defined as "unique". Without that validation, the graph shows a many-to-many relationship, which of course is a recipe for anarchy. But as a developer, can I use a UUID for primaries, ignore the fact that my graphs don't denote one-to-many relationships, and be confident that my app will not be broken?