I studied some persistent object store databases in the past - which seemed like an incredibly good idea and I think the AS400 used such a database and was very

I studied some persistent object store databases in the past - which seemed like an incredibly good idea and I think the AS400 used such a database and was very popular. It removed the need for a filesystem or any of the usual patterns for retrieving data like SQL so a whole class of programming that people think of as "normal" today just vaporised. Persistent programs seem like a logical-ish next step but I wish the first step could have been taken because it was very nice to program in.