COMET: An Efficient and Scalable Trajectory Data Management System

位置感知设备的使用，如带有GPS的手机或带有RFID(射频识别)标签的物体，在许多新兴的时空应用中正在爆炸式增长。传统的数据库管理系统(DBMS)不能处理这样的应用程序，特别是当应用程序需要管理大量移动对象时。COMET(不断演变轨迹管理)项目的目标是设计、实施和建立一个数据库管理系统，用于管理持续演变轨迹数据集的大型存储库。因为在这些环境中，位置更新是连续发布的，所以DBMS必须支持极其高效的方法来处理更新。此外，为了允许查询移动对象的先前位置，DBMS必须跟踪过去的轨迹。随着时间的推移，这些轨迹的长度不断增加，并且随着移动对象的数量不断增加，数据库的大小可能会急剧增加。因此，后端DBMS必须部署可伸缩技术来处理不断增加的数据大小和越来越多的移动对象。Comet项目的重点是开发高效和可扩展的方法来查询移动对象的过去、现在和未来位置，以及在这种环境中的可扩展触发机制。该项目的预期成果可能会对新出现的基于通知的应用程序产生重大影响，如应急系统，其中关键数据需要根据用户当前和不断变化的空间位置传播给实际移动用户。该项目还将培养一批研究生和本科生。项目网站(http://www.eecs.umich.edu/~jignesh/comet))将用于向广泛的研究社区免费提供COMET软件、所有开发的应用程序和真实的用户移动数据。

The use of location-aware devices, such as cell phones with GPS or objects with RFID (Radio Frequency Identification) tags, is exploding in a number of emerging spatio-temporal applications. Traditional database management systems (DBMS) are not designed to handle such applications, especially if the application requires managing a large number of moving objects. The goal of the COMET (Continuous Management of Evolving Trajectories) project is to design, implement, and build a database management system for managing large repositories of continuously evolving trajectories data sets. Since in these environments location updates are issued continually, the DBMS must support extremely efficient methods for dealing with updates. In addition, to allow querying on previous locations of the moving objects, the DBMS must keep track of past trajectories. As time passes these trajectories continue to increase in length, and with large and often increasing number of moving objects, the database size can increase dramatically. Consequently, the backend DBMS must deploy scalable techniques to deal with increasing data sizes, and increasing number of mobile objects. The key focus of the COMET project is on developing efficient and scalable methods for querying on past, present, and future locations of moving objects, and on scalable trigger mechanism in this environment. The expected results of this project may have a strong impact on emerging notification-based applications, such as emergency response systems, in which critical data needs to be disseminated to a physical mobile user based on the user's current and changing spatial location. The project will also train a number of graduate and undergraduate students. The project Web site (http://www.eecs.umich.edu/~jignesh/comet) will be used for making the COMET software, all developed applications, and real user movement data freely available to a broad research community.