“…Most of the previous works on real-time database systems are concentrated on soft real-time systems, such as stock trading systems (Adelberg et al, 1995;Amirijoo et al, 2006;Kang et al, 2004) and traffic information systems, with the main performance goal to maximize the average performance of the systems, e.g., minimizing the number of deadline missing transactions or maximizing the freshness of data objects (Shanker et al, 2008;Kang et al, 2009;Ramamritham et al, 2004;Lam and Kuo, 2001;Lam et al, 2002;Abbott and Garcia-Molina, 1992). With the rapid advancements in wireless communication and sensor technologies in recent years, real-time database technologies are gaining increasing interests for applications into various time-critical surveillance systems.…”