Research On Directional Nearest Neighbor Query Based On Spatial Database

In recent years,spatial database query technology has taken an increasingly important part in many fields,such as intelligent identification system and geographic information system.In spatial database,neighbor query is a kind of important query types.However,because of the nearest neighbor query's failure to meet the actual needs,the research direction of nearest neighbor query has changed from ideal environment to complex obstacle environment.Since there is no solution to query geographical direction in the existing nearest neighbor research,this paper focuses on the query method of directional nearest neighbor based on European environment and obstacle environment in spatial database.Firstly,For the nearest nearest neighbor query method,the nearest neighbor query problem of a specified geographic direction space cannot be directly performed,this paper proposes a directional nearest neighbor query method.In this paper,we study from two conditions.One situation is that the query point is static,and the other is that the query point is moving at a uniform speed.When the query point is static,the corresponding pruning rules and algorithm are proposed by combining the rectangular coordinate system with the east,west,south,and north directions.And then,according to the nature of the minimum circumscribed rectangle of the Voronoi polygon,the specific query is further carried out,and then the algorithm is given.In the case of the query point doing uniform motion,the scope of the query is determined by using the combination of plane rectangular coordinate system,east-west-north-south direction and circle.Then,according to the positional relationship between motion trajectory and Voronoi diagram,the specific query is carried out by using the nature of Voronoi graph.Furthermore,it is impossible to directly solve the nearest neighbor query problem in a specified geographic direction space under the obstacle environmentwith the existing nearest neighbor query method.Therefore,the nearest neighbor query method in the obstacle environment is proposed.Specifically,the research is divided into data pre-processing process and query process.Based on the combination of the plane rectangular coordinate system and the east-south direction,the data pre-processing process features with the proposal of corresponding pruning method and algorithm Pruning?ODNN.In the query process,the pruned data set and the positional relationship between the query point q and the Voronoi diagram are respectively used to generate different decision sectors,and the final direction nearest neighbor is determined in the decision fan shape.Theoretical research and experiments show that the proposed algorithm can effectively deal with the nearest neighbor query problem.