Hi, I want to develope a unique sequence id generator product, I have the following code def newid(self, increment=1): """ return new id """ self.counter = self.counter+increment return self.counter I am not quite sure if this works when more than one process asking for a newid concurrently. Is that zodb automatically serial all transaction? BTW, how can I obtain a local copy of the zodb uml model? Rgs, Kent Sin --------------------------------- kentsin.weblogs.com kentsin.imeme.net