A Method for Equijoin Queries in Distributed Relational Databases

A simple and efficient method for processing general equijoin queries in a distributed relational database is described. The query is first decomposed into a set of simple queries, each being involved with only one of the joining domains and its relevant equijoins. An extended version of Hevner and Yao´s STRATEGY PARALLEL or STRATEGY SERIAL is then applied on each of them for generating transmission schedules. These schedules will fully reduce (with respect to a simple query) some specified relations. The latter are then transmitted to the result site for final processing. In the case of minimizing total time, our method has a lower order of complexity than ALGORITHM GENERAL studied by Hevner and Apers. Examples show that our method gives better and more efficient solutions than theirs.