Hacker News Reader

> The remaining of the UUID value comes from the MD5 of a random value and the current time at a precision of 1us.

I might be misunderstanding something here but if your random seed is based on time, under high-concurrency, doesn't this risk collisions? I can't see any thread-safety guarantees in the documentation.[1]

[1] https://dev.mysql.com/doc/refman/8.0/en/mathematical-functio...

View on HN

If the column is UNIQUE there’s no collisions it will just fail to INSERT.

Then it doesn't have the same quality as a UUID which is supposedly guaranteed to be unique across space _and_ time[1].

[1] https://datatracker.ietf.org/doc/html/rfc4122

It’s not guaranteed, it’s just extremely probable that it’s unique given that its generation follows a uniformly random distribution.

Reply on news.ycombinator.com