Just a note about using uuid as a primary key. Typically you will use a b-tree index, which likes to keep things sorted. So something like a serial number works best, because it is already sorted and will be appended at the end. Otherwise inserting a new column will cause traversal the b-tree all over the place which will hurt performance it you do a lot of inserts.
If you really want to use uuid and care about performance you might prefix it with something that's increasing like a date, or perhaps (did not try it) use hash index (need to be PG 10+).
