Models and issues in data stream systems
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Issues in data stream management
ACM SIGMOD Record
Continuously Maintaining Quantile Summaries of the Most Recent N Elements over a Data Stream
ICDE '04 Proceedings of the 20th International Conference on Data Engineering
Approximate counts and quantiles over sliding windows
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
A heartbeat mechanism and its application in gigascope
VLDB '05 Proceedings of the 31st international conference on Very large data bases
SPADE: the system s declarative stream processing engine
Proceedings of the 2008 ACM SIGMOD international conference on Management of data
Semantics and implementation of continuous sliding window queries over data streams
ACM Transactions on Database Systems (TODS)
Window specification over data streams
EDBT'06 Proceedings of the 2006 international conference on Current Trends in Database Technology
Changing flights in mid-air: a model for safely modifying continuous queries
Proceedings of the 2011 ACM SIGMOD International Conference on Management of data
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Today, data stream management systems (DSMSs) mainly support the processing of data stream windows of static size. In the application domain of health monitoring, processing of data streams from body sensor networks can benefit from adapting to physiological processes of the human body, e.g., the heartbeat. This requires the introduction of time-based sliding windows of adaptive "size" in DSMSs. We have compared an existing algorithm with fixed sized windows for the identification of myocardial ischemia, a precursor to heart attacks, with a new version based on adaptive sized windows. The size of the sliding window over the heart acceleration stream was adapted to events in an electrocardiogram data stream that identifies heartbeats. This enabled that accelerometer readings originating from the same heartbeat were calculated in the same batch, as opposed to fixed size batches with no real relation to the continuous variable durability of each heartbeat. As a result, we obtained results with substantially less variance. We present in this paper the design and implementation of our adaptive window technique using the DSMS Esper. We measure both, the improvements of the medical analysis results and the overhead in terms of extra processing. The evaluation results indicate that the technique leads to considerably better medical analysis results in our case studies, and that the overhead introduced by handling the window technique itself is quite low.