Continuous Path-based Range Keyword Queries on Road Networks

In this paper, we study the continuous path-based range keyword queries, which find the answer set continuously when the query point q moves along a given path P on the road network. This type of queries have many real applications, whereas leading to challenges as issuing the query at each point on P is expensive and infeasible. To answer the query, we transform it to the issue of identifying a set of event points. Specifically, the event point captures the query point where the answer set changes, and query points between two adjacent event points share the same answer set. To identify event points efficiently, we develop a backbone network index (BNI) over a simplified network topology, which supports efficient distance computations and offers insights for keyword tests. Moreover, we develop a two-phase progressive (TPP) query processing framework over BNI. The first phase performs range keyword queries to get answer sets for a fraction of vertices on P. Note that this can be achieved by only issuing the query once. In the second phase, event points are identified with these retrieved answer sets. Extensive experiments on both real and synthetic datasets show that our algorithm outperforms competitor by several orders of magnitude.