Vaguely related story: I inherited a system which generates SSCCs to identify each box being shipped from a warehouse. These are supposed to be globally unique,

Vaguely related story: I inherited a system which generates SSCCs to identify each box being shipped from a warehouse. These are supposed to be globally unique, and are generated from a company's GS1 number (the same used for UPCs) plus another number which the company is supposed to make sure is unique. This particular system generated them on the client-side, based on the current timestamp in microseconds, with a random pause to prevent two computers from generating identical runs if they both printed labels at the same time. In a fairly small warehouse, this generated collisions about every six months or so. I instead changed the program to use an (already existing!) auto-increment column on the shared database, thus precluding any possibility of collision and making the program a lot faster since it was no longer delaying for a quarter-second per label (on shipments of 200+ boxes).