Classes that extend the Optimistic trait will have an optimistic concurrency control policy enforced.
The Optimistic trait has the Int field occVersionNumber that gets incremented on each update, when updating via table[T].update(t:T), a StaleUpdateException is thrown if the row has been updated since ‘t’ was fetched (i.e. if the occVersionNumber does not match the value it was fetched with).
As can be seen below the org.squeryl.Optimistic trait has a self type declaration of KeyedEntity, which means that a class must extend KeyedEntity in order extend Optimistic.
The Table[A] class have the methods forceUpdate(a:A) and forceUpdate(a: Iterable[A]) to bypass the OCC mechanism