>Adding a surrogate key to such a table just adds overhead, although that could be useful >in case specific rows need updating or deleting without also modifying the other rows with >that same data - normally, only insertions and selections happen on such tables though, >and updates or deletes are absolutely forbidden - corrections happen by inserting rows with >an opposite transaction.
I routinely add surrogate keys like serial col to a table already having a nice candidate keys to make it easy to join tables. SQL starts looking ungainly when you have a 3 col primary key and need to join it with child tables.
I was always of the opinion that a mandatory surrogate key (as you describe) is good practice.
Sure there may be a unique key according to business logic (which may be consist of those "ungainly" multiple columns), but guess what, business logic changes, and then you're screwed! So using a primary key whose sole purpose is to be a primary key makes perfect sense to me.
