I'm used to Postgres, which doesn't have clustered key. If this is MySQL and you're using a clustered key, pkey is still how you'd identify rows in foreign keys

I'm used to Postgres, which doesn't have clustered key. If this is MySQL and you're using a clustered key, pkey is still how you'd identify rows in foreign keys etc, so I think the same advice of bigserial pkey applies. We learned using natural pkeys in college, which in practice burned me enough that I'll never do it anymore. I just set some uniqueness constraints.