Updating and Querying Databases that Track Mobile Units
Distributed and Parallel Databases - Special issue on mobile data management and applications
Adaptive push-pull: disseminating dynamic web data
Proceedings of the 10th international conference on World Wide Web
A Comparison of Protocols for Updating Location Information
Cluster Computing
IEEE Transactions on Computers
Locating Objects in Mobile Computing
IEEE Transactions on Knowledge and Data Engineering
Maintaining Temporal Consistency of Discrete Objects in Soft Real-Time Database Systems
IEEE Transactions on Computers
Modeling and Querying Moving Objects
ICDE '97 Proceedings of the Thirteenth International Conference on Data Engineering
Evaluating probabilistic queries over imprecise data
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Adaptive filters for continuous queries over distributed data streams
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
A Threshold-Based Algorithm for Continuous Monitoring of k Nearest Neighbors
IEEE Transactions on Knowledge and Data Engineering
Monitoring streams: a new class of data management applications
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Efficient IR-style keyword search over relational databases
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Partition-based lazy updates for continuous queries over moving objects
Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems
Adaptive Safe Regions for Continuous Spatial Queries over Moving Objects
DASFAA '09 Proceedings of the 14th International Conference on Database Systems for Advanced Applications
Location-dependent query processing: Where we are and where we are heading
ACM Computing Surveys (CSUR)
Efficient location updates for continuous queries over moving objects
Journal of Computer Science and Technology
Efficient Monitoring of Moving Mobile Device Range Queries using Dynamic Safe Regions
Proceedings of International Conference on Advances in Mobile Computing & Multimedia
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In a moving-object database system that supports continuous queries (CQ), an important problem is to keep the location data consistent with the actual locations of the entities being monitored, in order to produce correct query results. This goal is often difficult to achieve due to limited network resources. However, if an object is not required by any query, its value need not be refreshed. Based on this observation, we redefine the notion of temporal consistency of data items with respect to the query result, where only data items that are relevant to the CQs need to be fresh. To exploit this correctness definition, we develop an adaptive time-based update technique called query-result update (QRU). The advantage of this technique is that it identifies objects with different levels of significance to the correctness of query results. Locations of objects that have more impact to the query result are acquired more frequently than the ones that do not. To achieve this objective, queries are classified into rank-based (i.e., ranks of objects are critical to query results) and non-rank-based. For each query class, QRU decides the time instant that an object should send a location update based on the predicted impact of the object to the query result. Moreover, the location update frequency of each object is continuously adjusted in order to adapt to the accuracy of the prediction model used. We evaluate the effectiveness of QRU by simulating execution of CQs over synthetic and real data sets. We also compare QRU experimentally with existing location update policies, namely the distance-based method, the time-based method, the speed dead-reckoning method, as well as the safe region strategy.