For the last 5 years, the Gamma database machine project has focused on issues associated with the design and implementation of highly parallel database machines. In a number of ways, the design of Gamma is based on what we learned from our earlier database machine DIRECT [DEWI79]. While DIRECT demonstrated that paral- lelism could be successfully applied to processing database operations, it had a number of serious design deficiencies that made scaling of the architecture to 100s of processors impossible; primarily the use of shared memory and centralized control for the execution of its parallel algorithms [BITT83]
