How to implement “autoincrement” on Google AppEngine

Question

I have to label something in a \"strong monotone increasing\" fashion. Be it Invoice Numbers, shipping label numbers or the like.

1. A number MUST NOT BE used twi

Answer 1

Remember: Sharding increases the probability that you will get a unique, auto-increment value, but does not guarantee it. Please take Nick's advice if you MUST have a unique auto-incrment.