When reading the literature on declarative programming technology. A particular technology that sounded promising is active databases. It essentially allows the programmer to specify rules about data that generate more data. On face value it seems like a great thing to have when compared to your neighborhood average imperative code.
There are many production rules systems out there, but they are not integrated with a database system. As I understand it, active databases would have been the logical evolution for production systems.
But, the subject seems to have died off. It is hard to find articles on Active Databases. And I can't really find a product that implements anything like that. My question is, what happened?