Not OP, but over 24 years some major db upgrades may as well be an entirely new db. In addition database vendors go out of business and when their assets are bought, the buyer is often buying customer base and not so much the obligation to keep developing a separate product forever. E.g. IBM and Oracle have each bought lots of their prior competition, and sometimes they only offer customers an upgrade path to a different product. Each time something like that happens you are going to re write your db support anyway.