What happens when DB engine runs out of numbers to use for primary keys?

Question

Since DBs do not reuse numbers of deleted records it is possible to run out of numbers, especially if you pick not really a big integer type for this column.
What would

Answer 1

I think exactly what happens will be dependent on which database engine you're using (there may even be differences between INNODB and MyISAM in MySQL). Whatever happens, it's not going to be pretty.

You'd simply have to change the column type to a larger integer.