It's not super unreasonable for a multi-element primary key, is it? For example, at work we have a MySQL table that stores advertising stats with a (Publisher I

It's not super unreasonable for a multi-element primary key, is it? For example, at work we have a MySQL table that stores advertising stats with a (Publisher ID, Country, Day) primary key[1]. All those fields are non-nullable, but I can imagine someone using NULL for the country[2] if we couldn't determine it (it's based on IP). [1] It's slightly more complicated, but it's basically similar. [2] "zz" might be appropriate to represent an unknown country, but other domains might not have a good default value Edit: double asterisks messing up my formatting