A model for XQuery-based GML spatial index and query

Abstract

This paper separates the GML document into structure and content according to the XML's semi-structure feature, and optimizes them individually. On the one hand, we adopt extending coding scheme based on full k ary tree to quantitate the nodes which present GML path information, then optimize the path expression with POEM(Path Oriented Extensible Model) to improve query efficiency. On the other hand, to GML contents stored separately as node sets, we study GML spatial index based on R-tree and establish GML spatial data index for spatial data. Concerning GML query, This paper considers that the key of GML query is how to deal with the spatial relational query,except for querying spatial data attribute. So by integrating the characteristics of spatial data, we give a suit of expanded query functions, including basic operation functions, spatial relational operation and spatial analysis functions. Finally we expand XQuery and realize a query system based on an opening source code software-XQEngine. Our experimental results show that the GML spatial query method based on full k ray tree expanding coding and R-tree spatial index can meet spatial query effectively.