To understand all the benefits and pitfalls of reactive persistence, first we have to recap on how applications have been implementing data access in the pre-reactive era. We also have to learn how a client and a database communicate when issuing and processing queries, what parts of such communication could be done asynchronously, and what parts could benefit from applying reactive programming patterns. As database persistence consists of a few layers of abstraction, we are going to go through all of these layers, describing them and trying on the reactive outfit.