Re: pervasiveness of surrogate (also called synthetic) keys

otoh, there's plenty of places where natural keys are optimal.   my
company makes widgets, and we make damn sure our serial #s and part
numbers are unique, and we use them as PK's for the various tables.
further, the PN has a N digit prefix which is unique to a part family,
then a M digit suffix which identifies a specific version of that PN.
we use the N digit PN for the family tables, and the full N+M digit PN
for the full PN tables.   serial # is globally unique across all PNs so
its the PK of any table related directly to a widget.