[naniwaduni]

I think by the time you're building a system that needs to generate (and persist!) billions of identifiers per millisecond, you're solidly past the point where all your design decisions need to be vetted for whether they make sense on your extremely exotic setup.

[tremon]

But 12 bits is not "billions of identifiers" -- it's 4096. Once you exhaust that counter in the same millisecond, you are still relying on a gamble that your random source will not generate the exact same bit sequence for the previous same counter value. And this thread started out with the OP explaining that random collisions are much more common than we'd like them to be, for various reasons.