Primary Key Efficiency

Not sure if this is relevant to SQL Server Mobile or SQL Server 2005, but still interesting nonetheless. The key takeaway seems to be that the primary key should be single column if possible and an int datatype (link).

Also, from link, "A primary key is an attribute (or combination of attributes) that uniquely identify each instance of an entity. A primary key cannot be null and the value assigned to a primary key should not change over time. A primary key also needs to be efficient. For example, a primary key that is associated with an INTEGER datatype will be more efficient than one that is associated with a CHAR datatype. Primary keys should also be non-intelligent; that is, their values should be assigned arbitrarily without any hidden meaning. Sometimes none of the attributes of an entity are sufficient to meet the criteria of an effective primary key. In this case the database designer is best served by creating an "artificial" primary key."