covering Primary Keys.. What's too much

SQL Apprentice Question
I have a table which I'd like to create a Primary Key that would have to
cover 6 fields to enforce uniqueness.
My question is, is that too much. I know it's common to have tables with
PK's that cover 2-3 fields, but 6 seems like a little much. [3 int fields, 2
varchar(5) fields, 1 tinyint]
I know I can use a surrogate "ID" identity field as the PK, but I prefer to
use PK's that are more natural if possible.

Any thoughts on this?



Celko Answers

>> I have a table which I'd like to create a Primary Key that would have to cover 6 fields [sic] to enforce uniqueness. My question is, is that too much. <<


This is rare but possible. Since we do not have any specs or knwo
anything about the problem, all we can do is generalize. I have seen
some people create super-keys (sertial number + manufacturer, not
knowning that serial number has manufacturer in it).


>> I know I can use a surrogate "ID" identity field as the PK, but I prefer to use PK's that are more natural if possible. <<


1) it is not a surrogate key because it is exposed to the user; that is
the definition from Dr. Codd.

2) you will need to use a UNIQUE (c1,.. ,c6) constraint anyway, so you
now have two indexes


3) You will need code to assure that the IDENTITY is always validate
and points to the right target.