This is a good answer. You want your primary/cluster key to usually be something that makes sense in your data. If you use something like UUID the placement c

This is a good answer. You want your primary/cluster key to usually be something that makes sense in your data. If you use something like UUID the placement can be basically random. That is usually in SQL is not a desirable trait. If you use it for a primary key you are basically saying you are fine with a memory cmp vs a register compare for you finding the right data. That can be undesirable too. UUIDs do have very desirable traits such as uniqueness. But that does come at a cost and usually you can fix that by deciding what process decides the source of truth in a different way.