Yeah it's pointless to use locks if you have a single operation, but I

might want to do more operations in a single transaction.. actually

what's the point of using a transaction if I have only one operation?

WIthout transaction it is possible that the operation is only partially applied, i.e. on a subset of numOwners, resulting in inconsistent state.

Good point Mircea. You should definitely document that cos that's pretty much the sole reason to use implicit transactions, something users should know.