What are the design criteria for primary keys?

Question

Choosing good primary keys, candidate keys and the foreign keys that use them is a vitally important database design task -- as much art as science. The design task has very specific design criteria.

What are the criteria?

Answer 1

The criteria for consideration of a primary key are:

• Uniqueness
• Irreducibility (no subset of the key uniquely identifies a row in the table)
• Simplicity (so that relational representation & manipulation can be simpler)
• Stability (should not be altered frequently)
• Familiarity (meaningful to the user)