Optimization of Multi-Way Join Queries for Parallel Execution
Hongjun Lü, Ming-Chien Shan, Kian‐Lee Tan · 1991
Most of the existing relational database query optimizers generate multi-way join plans only from those linear ones to reduce the optimiza-tion overhead. For multiprocessor computer systems, this strategy seems inadequate since it may reduce the search space too much to gen-erate near-optimal plans. In this paper we present a framework for optimization of multi-way join queries in multiprocessor computer systems. The optimization process not only determines the order and method in which each join should be performed, but also determines the number of joins should be executed in paral-lel, and the number of processors should be allo-cated to each join. The preliminary performance study shows that the optimizer usually generate optimal or near-optimal plans when the number of joins is relatively small. Even when the number of joins increases, the algorithm still gives reasonably good performance. Further-more, the optimization overhead is much lesser compared to exhaustive search.