I seem to recall neo4j (could be it was another nosql db/company) had some strange ideas about the agpl. Of course if the drivers are covered by agpl and linked into your application, then you might have to create a new api "border" (eg:HTTP REST) between whatever code you want to license differently and the agpl server. I don't think the agpl should be a problem in most cases - at any rate you don't have to contribute patches up-stream, only to those of your users that ask for the code (if any). Unless upstream is also using your service, that is.
A perhaps more interesting question is how they manage contributions and pull requests - if i'm using the server under agpl, it seems natural to contribute code under agpl. But now that code can't be used in the commercially licensed upstream "fork" unless that fork is sold under the agpl... So either contributors will have to donate code, or sell code to upstream for use in the "closed" project.
I could see that get a bit hairy with user-contributed bug fixes?
A perhaps more interesting question is how they manage contributions and pull requests - if i'm using the server under agpl, it seems natural to contribute code under agpl. But now that code can't be used in the commercially licensed upstream "fork" unless that fork is sold under the agpl... So either contributors will have to donate code, or sell code to upstream for use in the "closed" project.
I could see that get a bit hairy with user-contributed bug fixes?