An Approach to Adaptive Memory Management in Data Stream Systems

Adaptivity is a challenging open issue in data stream management. In this paper, we tackle the problem of memory adaptivity inside a system executing temporal sliding window queries over continuous data streams. Two different techniques to control the memory usage at runtime are proposed which refer to changes in window sizes and time granularities. Both techniques differ from standard load shedding approaches based on sampling as they ensure precise query answers for user-defined Quality of Service (QoS) specifications, even under query re-optimization.