1. A stream data generating method for a computer system for generating stream data having time information applied thereto in a time series order and processing the generated stream data on the basis of a registered query, said computer system comprising: a storage for storing query information indicative of a plurality of sorts of constituent elements of the stream data corresponding to the query on the basis of the query and a stream definition indicative of the plurality of sorts of constituent elements of the stream data; a data generator for generating and transmitting the stream data; and a stream data processor for processing the stream data transmitted from the data generator, wherein said data generator executes a step of generating a less quantity of stream data from the stream data transmitted to the stream data processor on the basis of the query information.