You are asking very basic JPA questions and I don’t think this is the right place to ask these question.

I don’t want to be rude but maybe you should buy a book about JPA/Hibernate and read about the core concepts to understand this better. In general, optimistic locking requires a version field, that’s just how optimistic locking works. You could also use pessimistic locking which uses a database lock, but that only holds for the transaction lifetime.