Another point for large companies is essentially vendor lock-in. If you had Oracle 8 way back in the day (90's), then the upgrade and pay maintenance path is m

Another point for large companies is essentially vendor lock-in. If you had Oracle 8 way back in the day (90's), then the upgrade and pay maintenance path is much easier than even the thought of switching to a different system. Think of how much testing and conversion you would have to do to switch to Postgres. ANSI SQL is a standard but there are little shortcuts and tuning and other things that are very vendor specific. An upper management viewpoint would ask the question of what is the ROI of switching?