Algorithms for distributed query processing in broadcast local area networks

Distributed query-processing algorithms for broadcast local-area networks are described which provide execution strategies and estimates of response time. Four semijoin-specific techniques, five transmission-specific techniques, and three size estimation update functions are incorporated into a baseline algorithm. These variants of the baseline algorithm are simulated and their response times compared using randomly generated data. The technique found to be most beneficial, on the average, for general queries involving multiple joining attributes is the composite semijoining technique. When used in combination with composite semijoining, relation transmission and bit-matrix transmission further reduce response time. Bit-matrix transmission is a data compression technique in which single attributes and a bit matrix of the value pairings are sent in place of a composite attribute. The authors examine these techniques in detail and compare their expected response times