How to generate unique 64 bits integers from Python?

python guid random uniqueidentifier uuid
Continuation picture Continuation · Aug 20, 2010 · Viewed 37.9k times · Source

I need to generate unique 64 bits integers from Python. I've checked out the UUID module. But the UUID it generates are 128 bits integers. So that wouldn't work.

Do you know of any way to generate 64 bits unique integers within Python? Thanks.

Answer

John La Rooy picture John La Rooy · Aug 20, 2010

just mask the 128bit int

>>> import uuid
>>> uuid.uuid4().int & (1<<64)-1
9518405196747027403L
>>> uuid.uuid4().int & (1<<64)-1
12558137269921983654L

These are more or less random, so you have a tiny chance of a collision

Perhaps the first 64 bits of uuid1 is safer to use

>>> uuid.uuid1().int>>64
9392468011745350111L
>>> uuid.uuid1().int>>64
9407757923520418271L
>>> uuid.uuid1().int>>64
9418928317413528031L

These are largely based on the clock, so much less random but the uniqueness is better

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