Is there a way to have benefits of both? Version 7 for better database clustering. And version 4 for complete randomness? So users can not inference nothing from the id? I have an idea: Use version 7 internally, then scramble it before sending to the user. Scrambling could be done by the database or by the server application. It could be as simple as XOR with some 128bit constant, or as resilient as AES encryption. Of course you also need to do unscrambling of IDs coming from users.