Could one of the authors provide some more information about the goals and architecture? Do I understand it correctly that the goal is to implement a relational

Could one of the authors provide some more information about the goals and architecture? Do I understand it correctly that the goal is to implement a relational database on top of one of a couple of different key value stores and aiming, among other things, for drop in compatibility with MySQL? What are expected benefits? EDIT: The architecture diagram wasn't visible to me before, now that it suddenly appeared things are way more clear.