Recently I worked on a DB File Storage System that saved files under GUID ID's. I became curious what the odds were of the DB accidentally generating a duplicate GUID for two different files, so I did the math.
Here is what I found:
Number of Possible 128bit GUIDs:340,282,366,920,938,000,000,000,000,000,000,000,000
Number of seconds in the age of the universe (15 billion years)
(Divide the first number by the second to get GUIDs per Second)
Number of GUIDs generated per second for life of universe:71,887,518,854,221
What this means is that we would need a battery of computers working 24/7 generating 71.9 quadrillion GUIDs per second for the entire life of the universe before we would find a duplicate GUID.
I get the feeling we don’t need to worry about duplicate GUIDs.