Tuesday, January 13, 2015



So today at work I wanted to uniquely identify a resource before storing it. There are many options our there, but I chose the standard UUID method which stands for Universally Unique IDentifier. But how unique is it really?! According to it's definition, depending on how it is generated, it is considered unique enough so that the chance of someone else ever generating another UUID by chance that matches the one you generated is extremely low.

It turns out there can be three hundred and fourty undecillion, two hundred and eighty two decillion, three hundred and sixty six nonillion, nine hundred and twenty octillion, nine hundred and thirty eight septillion, four hundred and sixty three sextillion, four hundred and sixty three quintillion, three hundred and seventy four quadrillion, six hundred and seven trillion, four hundred thirty one billion, seven hundred sixty eight million, two hundred and eleven thousand, four hundred fifty six possible values for a universally unique identifier. That is 340,282,366,920,938,463,463,374,607,431,768,211,456! Or, 2^128 for short.

That is larger than the number of stars in the observable universe. I think that is unique enough. :)

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