What happens when you choose the wrong Datatype for an Identifier Column
Choosing database column data types can be dicey. Choose an overly large data type, and indexes will be overly large, storage will fill up and other bad things can happen.
Choose an overly small one, and you end up with hard errors.
A common data type for a database identity column is an int. However, if your application gets popular, it can break. Pastebin is a victim of it's own success :)