Architectural Considerations For Parallel Query Evaluation Algorithms

Parallelism is key to high performance relational database systems. Since there are several parallel architectures suitable for database systems, a few interesting problems arise, mostly from an emphasis on the differences among the architectures. Specifically, in the literature, differences rather than similarities between the architectures are pointed out, and the specific details of a particular architecture, crucial to high performance, are generally ignored. In this thesis we have attempted to remedy this situation by emphasizing the similarities and a deeper understanding of two popular parallel architectures, shared nothing and shared memory, from a database perspective. We show that there is complementarity and similarity in the two architectures by showing that software shared-memory support can be used to improve performance on shared-nothing hardware and by showing that shared-nothing software can run on shared-memory hardware with performance comparable to that of "native" ..