Chimera: data sharing flexibility, shared nothing simplicity

The current database market is fairly evenly split between shared nothing and data sharing systems. While shared nothing systems are easier to build and scale, data sharing systems have advantages in load balancing. In this paper we explore adding data sharing functionality as an extension to a shared nothing database system. Our approach isolates the data sharing functionality from the rest of the system and relies on well-studied, robust techniques to provide the data sharing extension. This reduces the difficulty in providing data sharing functionality, yet provides much of the flexibility of a data sharing system. We present the design and implementation of Chimera -- a hybrid database system, targeted at load balancing for many workloads, and scale-out for read-mostly workloads. The results of our experiments demonstrate that we can achieve almost linear scalability and effective load balancing with less than 2% overhead during normal operation.