Is mysql auto increment safe to use as userID?

Question

I am working on website that allows people to create profiles online. I was wondering if it is the right choice to use MySQL AUTO_INCREMENTed IDs as my user ids

Answer 1

No, it is not a good idea because auto_increment ids are not easily portable. For your user ids you want ids that can be backed up, restored, moved between database instances, etc. without worrying about collision of ids.

It would be better to generate a unique number or alpha-numeric string using something like UUID.