I think thats a business decision, not a technical one. You have to decide what odds you are willing to accept, based on how many records you anticipate, how h

I think thats a business decision, not a technical one. You have to decide what odds you are willing to accept, based on how many records you anticipate, how hard it will be to increase the length if that estimation is wrong, and how bad it would be if there was a collision. In any case though, there are certainly many bad things which could happen to your company which are more likely than 1 in a million.