How unique are Uuid's?

[dave96]

Bit of a silly question here but I’m just wondering if its ok to just create these to uniquely identify properties or if some additional protection is usually implemented such as caching and checking all the previously created Uuid’s?

In my use-case these could also be created on different computers and compared centrally so providing this extra check would again minimise the risk of duplicates but I feel I’m just being paranoid now.

I guess the obvious advice is: yes, they are almost guaranteed to be unique but be prepared to cope with duplicates if necessary?

[jules]

I think you’d have to be spectacularly unlucky to get the same one twice!

[dave96]

I’ve never won at Minesweeper.

[TheVinn]

Assume there will never be a collision.

[sylfeline]

Read this article on Wikipedia, and you’ll understand, that uuid is enough unique

[dave96]

only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. The probability of one duplicate would be about 50% if every person on earth owns 600 million UUIDs.

Ok thanks, I guess its pretty safe to assume their unique then.

[atom]

I managed to hit a duplicate with CRC32 when Introjucer was in early stages, we found two file paths that gave the same CRC32 checksum if i remember correctly, but UUIDs are way more safer then just a CRC32.