Output Rate

Assuming the filters of the query have selectivity S, then the computational network (the optimized continuous queries plan) generates an output tuple with probability S every C time units. Therefore the guaranteed output rate is:

where S is calculated as the multiplication of the individual operators selectivity along the path of a single tuple, that is:

where si is the selectivity of operator I, and C is the expected cost. Assuming that our QoS/QoD adaptive algorithm uses mtb1 at q of the time, while it uses mtb2 (1-q) of the time, and the cost of mtb1 and mtb2 at operator i to be ci1 and ci2 respectively, then the expected cost C is calculated as the cost of the first operator plus the cost of the second operator if it made it through the first operator and so on. Thus the total cost is: