[fpc-pascal] GUIDs under FreeBSD don't seem very random

Graeme Geldenhuys mailinglists at geldenhuys.co.uk
Wed Jan 6 01:14:01 CET 2016

On 2016-01-05 23:56, Graeme Geldenhuys wrote:
> From Wikipedia (GUID vs UUID)
> -----------------------------
> The term GUID usually refers to Microsoft's implementation of the
> Universally Unique Identifier (UUID) standard.

Reading further on Wikipedia I now understand you get different versions
of UUID's. My first set of values were Version 1 (MAC address &
date-time) type, and the second set was a Version 4 (Random) set.

That explains why they looked so different.

> So am I to assume that I will still get unique values even if I generate
> 1-2 million records in succession?

>From the Wikipedia explanation on how Version 1 UUID's are generated I
think it is safe to assume that generating 1-2 million UUID's (aka
GUID's) is succession should be fine and the likelihood of duplicates
are still extremely small.

Probability of duplicates (also from Wikipedia)
To put these numbers into perspective, the annual risk of a given person
being hit by a meteorite is estimated to be one chance in 17 billion,
which means the probability is about 0.00000000006 (6 × 10−11),
equivalent to the odds of creating a few tens of trillions of UUIDs in a
year and having one duplicate.

That's odds I'll accept for now. ;-)

[Sorry for the mailing list noise. It seems with my own research (after
my initial post) I now managed to answered my own question.]

  - Graeme -

fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal

My public PGP key:  http://tinyurl.com/graeme-pgp

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