Expressive Location-Based Continuous Query Evaluation with Binary Decision Diagrams

Many location-based services require rich and expressive query language support for filtering large amounts of information. In prominent location-based services thousands of continuous queries execute concurrently. Parts of these queries may overlap or logically depend on each other suggesting to amortize the execution over shared sub-queries and ordering queries according to their dependency relations. In this paper spatio-temporal queries constitute location constraints monitored by applications. We develop Constraint Combination Binary Decision Diagrams (CCBDDs), an efficient location constraint matching algorithm based on Binary Decision Diagrams. With CCBDDs, redundant computations for shared sub-queries are avoided, and query dependencies are identified and pruned. Empirical results show that the CCBDD structure greatly improves matching performance by eliminating otherwise redundant computation and memory use in the evaluation.

• Type: Conference
• Year: 2009
• Where: ICDE
• Authors: Zhengdao Xu, Hans-Arno Jacobsen
• Keywords: Binary Decision Diagrams, Combination Binary Decision, Constraint Matching Algorithm, Continuous Queries, Database, ICDE 2009, Queries Constitute Location