基于Ex-Dewey前缀编码与R树的GML空间数据索引机制  

GML Spatial Data Index Mechanism Based on Ex-Dewey Prefix Encoding and R-tree

作　　者：陈建华[1,2] 王卫红[3] 苗放[2] 

机构地区：[1]电子科技大学地表空间信息技术研究所,成都610054 [2]成都理工大学信息工程学院,成都610059 [3]成都理工大学地球科学学院,成都610059

出　　处：《地球信息科学学报》2010年第2期186-193,共8页Journal of Geo-information Science

基　　金：四川省教育厅科学基金项目(编号:2006A117)

摘　　要：大量GML空间数据的出现,使其有效性的查询处理面临严峻挑战。索引技术是决定数据查询性能的重要因素之一。鉴于GML空间数据XML格式编码的特点,为充分利用Dewey前缀编码方案并消除原方案中节点的插入、删除影响其后趋同胞节点及其子孙节点编码的变更等缺点,论文提出了一种扩展的Dewey编码方案——Ex-Dewey,用以实现对GML文档数据的整体编码和非空间数据的索引构建。研究给出了Ex-Dewey前缀编码的GML非空间数据索引构成模式与处理策略;结合Ex-Dewey,提出GML空间数据索引基于R树的构建,给出了索引构成模式与处理策略。GML空间与非空间数据索引构建,既独立又紧密关联,共同实现GML空间数据的索引。该索引机制意在用于原生GML空间数据库索引构建或单纯GML文档集索引构建中。Severe challenges are faced by GML spatial data effective query processing while masses of GML spatial data are being produced.While,to query GML spatial data effectively,index is one of the key factors which control the data query performance.Considering XML format encoding style of GML spatial data,in order to take full advantages of Dewey prefix encoding scheme and achieve its new updating strategy that node＇s inserting and deleting do not effecting others＇ encoding values,a kind of extended Dewey encoding scheme,Ex-Dewey,was proposed,which is intended to encode the whole GML spatial data documents and construct index to GML non-spatial data.The construction model and processing strategy of non-spatial data index based on Ex-Dewey were well given and discussed.The whole nodes in GML spatial data document firstly are encoded based on Ex-Dewey,and GML non-spatial data index is constructed with three levels,the nodes index can be queried,inserted,modified and deleted while GML non-spatial data were correspondingly operated.Combining with Ex-Dewey,GML spatial data index construction mechanism based on R-tree was proposed,and its construction model and processing strategy were also well given and discussed.The whole GML features in GML spatial data document are the spatial objects.Extracting every GML feature＇s spatial coordinates and constructing its minimum boundary rectangle（that is MBR）,the MBR and its feature＇s Ex-Dewey encoding value are set as the parameters of R-tree functions.Using R-tree spatial index construction functions with MBR and encoding value,the GML spatial data＇s index are constructed.Then,all spatial data index＇s query,insertion,modification and deletion can be operated using R-tree functions with GML feature＇s MBR and encoding value.Ex-Dewey and R-tree are independent and closely related between GML spatial and non-spatial data index constructions,which integrally implement index mechanism of GML data.Using this index mechanism,GML spatial and non-spatial data can be queried

关 键 词：GML空间数据 索引 Ex-Dewey前缀编码 R树 

分 类 号：TP311.13[自动化与计算机技术—计算机软件与理论]