This is a question a lot of people are asking me, and I keep give them the same answer. “I am the one building RavenDB, your grandmother and all her cats deserve to have three licenses, each (maybe with 3 way replication as well).”
Kidding aside, it is a serious question, which I am going to try answering in this post. I just wanted to make sure that it is clear that there might be some bias from my perspective.
Having built NHibernate based application for years, and having built RavenDB based applications from almost the point where it could start up on its own, I can tell you that there is quite a bit of a difference between the two. Mostly because I intentionally designed RavenDB and the RavenDB client API to deal with problems and frustrations in the NHibernate / RDMBS model.
What we discovered is that the lack of mapping and the ability to store complex object graphs in a single document makes for a speedy development and high performance applications. We usually see RavenDB being used in OLTP applications or as a persistent view model store (usually for the performance critical pages).
Typically, it isn’t the only database in the project. In brown field projects, we usually see RavenDB brought in to serve as a persistent view model store for the critical pages, data is replicated to RavenDB from the main database and then read directly from RavenDB in order to process the perf critical pages. For green field projects, we usually see RavenDB used as the primary application database, most or all of the data resides inside RavenDB. In some cases, there is also an additional reporting database as well.
So the quick answer, and the one we are following, is that RavenDB is imminently suitable for OLTP applications, and can be used with great success as a persistent view model cache.