hashtypesconflictuuidbit
How to calculate the risk of conflicts of a 64 bit hash?
I need global unique ids for my application. I know there is an UUID standard for this, but I wonder if I really need 128 bits.
So I think about writing my own generator that uses system time, a random number, and the machines network address to generate an id that fits into 64 bit and therefore, can be stored in the unsigned long long int datatype in C++.
How can I determine if 64 bits is enough for me?
Solution
64 bit runs to about 18,446,744,073,709,551,616 combinations which is around 18 and a half quintillion.
so if your'e generating 1.92 million hashes, the odds of a collision will be 1 in 10 million
Source: http://preshing.com/20110504/hash-collision-probabilities
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