Understanding How UUIDs Are Generated

After discovering ULIDs [0] I can&#x27;t see ever using UUIDs ever again.<p>ULIDs are sortable (time component), short (26 chars) and nearly human readable, and good enough entropy&#x2F;randomness for everything I&#x27;d ever be working on.<p>Does anyone have any criticisms of ULIDs? I can&#x27;t see how they don&#x27;t take over general purpose use of unique ids in the future except where a more guarantee of uniqueness is needed. (ie, bajillion records a second unique...)<p>[0] <a href="https:&#x2F;&#x2F;github.com&#x2F;ulid&#x2F;spec" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;ulid&#x2F;spec</a>

<a href="https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4122" rel="nofollow">https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4122</a> is good reading.

In my experience, &quot;UUID&quot; often means nothing more than &quot;take 16 bytes from a CSPRNG&quot;.

The different strategies are interesting, but I don&#x27;t understand the bit flags. Why would you want your ID to include a record of how it was generated? Some use cases go out of their way to obfuscate that information, and one selling point of UUID over auto increment is that you can&#x27;t infer missing items or how many are being created by watching PKs.<p>It&#x27;s cool that I can make deterministic UUIDs, but it seems silly that the spec should require me to expose the fact that it&#x27;s deterministic. It&#x27;s not like my deterministic UUID is any more likely to collide with someone else&#x27;s random one than two deterministic or two random are to collide with each other.

Xcuse me asking, but is there some standard way to make a copied partition in Ubuntu bootable as an unique entity? First you change the UUID in Gparted and then you waste an hour rebooting and hunting for references to that old UUID. Not good.

Along with the comments about ULIDs and KSUIDs, some people might want to check out C4 IDs. Webpage at <a href="http:&#x2F;&#x2F;www.cccc.io&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.cccc.io&#x2F;</a>, which has a link to its Github page.