Is there a measurable performance difference between using INT vs. VARCHAR as a primary key in MySQL? I’d like to use VARCHAR as the primary key for reference lists (think US States, Country Codes) and a coworker won’t budge on the INT AUTO_INCREMENT as a primary key for all tables.
My argument, as detailed here, is that the performance difference between INT and VARCHAR is negligible, since every INT foreign key reference will require a JOIN to make sense of the reference, a VARCHAR key will directly present the information.
So, does anyone have experience with this particular use-case and the performance concerns associated with it?