Originally posted by chrisrlong
Everytable needs a PK.
To every rule there is an exception, and here it is -- it is generally accepted that large data warehouse fact tables do not need a PK, mostly because

i) you can rely on rowid for unique identification, and
ii) you will not need to reference the table through a foreign key.

I expect that is not the case here however, so I'm just being pedantic.