in general, should every table in a database have an identity field to use as a PK?

Question

This seems like a duplicate even as I ask it, but I searched and didn\'t find it. It seems like a good question for SO -- even though I\'m sure I can find it on many blogs e

Answer 1

Almost always yes. I generally default to including an identity field unless there's a compelling reason not to. I rarely encounter such reasons, and the cost of the identity field is minimal, so generally I include.

Only thing I can think of off the top of my head where I didn't was a highly specialized database that was being used more as a datastore than a relational database where the DBMS was being used for nearly every feature except significant relational modelling. (It was a high volume, high turnover data buffer thing.)