通用映射模式下GML关系数据库存储研究

New model for storing GML document into relational database

提出了一种将GML文档存储到关系数据库的存储映射模型G2RDB,通过解析GML文档,提取文档的要素信息、空间对象信息和嵌套关系等,根据预先定义的映射规则和要素模型的映射关系表,形成GML数据文档与关系数据库之间的关系模式映射表:要素信息表、要素模型映射表、同类要素属性信息表和空间对象信息表,将文档数据存储到RDBMS中,实现了GML文档的关系数据库存储,同时生成了同样可用于其他GML实例数据的通用映射关系表模式。在关系数据库存储方式下,应用SQL和自开发的空间操作算子函数可以实现GML数据的查询,依据映射规则可将查询结果以重构为合法的GML文档或文档片断的形式返回。

This paper proposed a new model called G2RDB for storing GML data into RDBMS. Through parsing GML documents, G2RDB got geo-feature info, spatial object and nest relation described by its unique parent of every node. According to the predefined mapping rules and the mapping tables of geo-feature models, the proposed method could store GML data into RDB by the generated relational schemas that were mapping from GML document to four kinds of relational tables ： feature_info, featm mappingtab, feat att and doc_spatialObj. A prototype system of the proposed method had been implemented based on the syntactic and semantic database to show applicability for storing GML data. As a result, the implemented system can store various GML data which have diverse XML structures and different size. Also, comparison shows the advantages that GML data stored in RDB. Furthermore, spatial, non-spatial and mixed content queries can be performed over the stored GML data quickly, obtaining results, in the form of fragments of GML data or GML document.