Designed for complex event processing, DataCell is a research prototype database system in the area of sensor stream systems. Under development at CWI, it belongs to the MonetDB database system family. CWI researchers innovatively built a stream engine directly on top of a database kernel, thus exploiting and merging technologies from the stream world and the rich area of database literature. The results are very promising.
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Liarou, E., & Kersten, M. (2009). DataCell: Exploiting the Power of Relational Databases for Efficient Stream Processing. ERCIM News, (76).