Research And Implementation On XML Data Index In Relation-XML Dual Engine Database Management System CoSQLRX

As XML is becoming the standard of data release and exchange, it is urgently required a method to manage XML data efficiently. Due to historical reasons relational data still accounts for a large percentage of the market share. And single XML data management is not fit, and using relaional data and XML data mixed management is the main trend in aspect of data management now. CoSQLRX is a relation-XML daul engine database management system, which can deal with both relation query and xml query. XML index is an important component of CoSQLRX system, and play an important role in accelerating the process of XML query. This thesis forus on the study of XML index, and propose a specific XML index frame in CoSQLRX system after analysing kinds of XML index technique.Firstly, this thesis introduces some concept and related work about XML data index. XML index technique can be divided into many kinds, such as path index, values index, node index and so on, and any kind has its own special features. Proceeding from the indexed objects by xml index, this thesis mainly studies on XML structure index and XML value index. XML structure index is used to handle the structure infomation of XML document, including XML path information, XML parent-child information, XML ancestor-descendant information and so on. XML value index is used to deal with the text in XML document, for example xml attrubute text and leaf text.Secondly, this thesis gives a detailed introduction about the implementation and the design of XML index module. Because XML index is based on the XML native storage and has to be corresponded to the process of relational data, this thesis puts forward a intermediate index infomation storage structure named by XmlInfoRelation. In the thesis, XML Index is composed of XmlInfoRelation and tree type index, named by XNBTREE. XmlInfoRelaiton stores the information got from XML native storage structure, while XNBTREE, which uses B-Link tree structure, stores the keys and pointers of XML index.At last, this thesis introduces tests on the XML index module, gives analysis of the experiment results, points out some deficiencies, and evaluates the overall performance of XML index. All in all,the XML index has good expansibility and commonability, and can satisfy the general requirement of xml query.