eDAR Algorithm for Continuous KNN Queries Based on Pine

The continuous K nearest neighbor (CKNN) query is an important type of query that continuously finds the KNN to a query point on a given path. In this article we focus on moving queries issued on stationary objects in spatial network database (SNDB). The result of this type of query is a set of intervals (defined by split points) and their corresponding KNNs. This means that the KNN of an object travelling on one interval of the path remains the same all through that interval until it reaches a split point where its KNNs change. Existing methods for CKNN are based on Euclidean distances. In this article, we propose a new algorithm for answering CKNN in SNDB where the important measure for the shortest path is network distances rather than Euclidean distances. We propose DAR and eDAR algorithms to address CKNN queries based on the progressive incremental network expansion (PINE) technique. Our experiments show that the eDAR approach has better response time, and requires fewer shortest distance computations and KNN queries than approaches that are based on VN3 using IE.