The Research On Skyline Query Method In Spatial Databases

The question of spatial database query becomes the focus of research because spatial queries are more and more applied to various fields.Among them,skyline query in spatial query is becoming more and more widely used as a kind of user preference query.Queries in practical problems involve the change of dimension from low dimension to high dimension,the change from Euclidean space to obstacle space and the change of points from static state to dynamic.But the existing research results can not effectively solve these problems.Therefore,the focus of this paper is the skyline query in the multidimensional space and the skyline query in the obstacle space.Firstly,in view of the bad ability to handle dimensions of spatial skyline query methods in dealing with the problem of skyline query in the multidimensional space,the spatial skyline query method based on Hilbert-R tree in the multidimensional space is proposed.This method takes advantages of Hilbert-R tree which combines R-tree and Hilbert curve with high efficiency and dimensionality reduction.According to the number of query points,the spatial skyline query method under the condition of single query point(SQ-HSKY algorithm)and the spatial skyline query method under the condition of multi query points(MQP-HSKY algorithm)are given.The SQ-HSKY algorithm is divided into two processes to solve the skyline set.The two processes are filtering and refining.The MQP-HSKY algorithm pruning non skyline points using the idea of dominant decision circle.The query efficiency is greatly improved.Secondly,the spatial skyline query under the static query point environment in the multidimensional space of the above study is extended to the dynamic query point environment.According to the change of query point,ADD-HSKY algorithm under the condition of the dynamic increasing query points,DEL-HSKY algorithm under the condition of the dynamic reduced query points and MOV-HSKY algorithm under the condition of the dynamic moving query points are given.In view of the corresponding dynamic changes,the corresponding decision rules and query method are proposed.The query time is reduced.Finally,in order to solve the problem that the existing research results can not effectively deal with the spatial skyline query in obstructed space,the spatial skyline query method in obstructed space based on R~+-tree is proposed.The method uses two processes which are filtering process and refinement process.The filtering process uses R~+ tree quickly locating features to effectively prune away a large number of data points which are dominated.Refinement process mainly screens objects within the candidate set according to the obstacle distance and the topological relationship between data points and query points.Finally the skyline set can be got.