What happen in SQL 2005 when it run out of number for an autonumber column?

Question

What happen when SQL Server 2005 happen to reach the maximum for an IDENTITY column? Does it start from the beginning and start refilling the gap?

What is the behavior

Answer 1

You will be unable to insert new rows and will receive the error message listed above until you fix the problem. You can do this a number of ways. If you still have data and are using all the id's below the max, you will have to change the datatype. If the data is getting purged on a regular basis and you have a large gap that is not going to be used, you can reseed the identity number to the lowest number in that gap. For example,at a previous job,we were logging transactions. We had maybe 40-50 million per month, but we were purging everything older than 6 months, so every few years, the identity would get close to 2 Billion, but we would have nothing with an id below 1.5 billion, so we would reseed back to 0. Again it's possible that neither of these will work for you and you will have to find a different solution.