High-volume, high-speed data streams may overwhelm the capabilities of stream
processing systems; techniques such as data prioritization, avoidance of
unnecessary processing and on-demand result production may be necessary to
reduce processing requirements. However, the dynamic nature of data streams, in
terms of both rate and content, makes the application of such techniques
challenging. Such techniques have been addressed in the context of static and
centralized query optimization; however, they have not been fully addressed for
data stream management systems.