> 3) To support changing slugs (titles) you will have to keep all the old slugs as well (to redirect them to their new versions). With ids you don't have to do

> 3) To support changing slugs (titles) you will have to keep all the old slugs as well (to redirect them to their new versions). With ids you don't have to do this - ids have no reason to change. Which basically means a join in the database. While not terribly expensive, its a lot more involved than a simple column value check.