Whether you want to argue that the DB shouldn't have been designed that way is a mute point.  DBAs often have to clean up what others do and sometimes even make mistakes themselves - or least all the DBAs I know have at some point made at least 1 mistake.  Things that are easy are often overlooked and I think because identity is easy, this situation is not unrealistic.  I thought the article was a concise and easy to read warning to be wary of identities lurking in your DB because they are defined on integers. 

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