Calculating when an integer identity column will be exhausted

Last week, we had an interesting discussion with a client which data type an identity column on a table should have. We are working with this client on a redesign of an in-house LOB.

In particular, we were discussing one table that we expecting to have one to two new rows per second each day. The customer wanted to define the identity as bigint, while we said that integer (int) is enough and faster for sure. What would you think how long it takes until an integer column as identity will "explode" on this table? Two Month? Three Years?


Well, if we calculate with three changes per second it would actually take 23 years!


In case you find this Excel file useful, you can download it here.