A Research On XML Querying Based On Index

XML query is an important area of XML technology. Although achievements of XML index query research are made, there are some problems of XML query technology because of XML's inherent characteristic.This thesis takes focus on the technology of XML query. This thesis addresses several key technical problems of indexing and querying XML, major contributions of this thesis include:(1) Design a XML index updating Algorithm.XML index updating has been researched deeply, but XML index updating is not resolved well. This paper presents a XML index pathvalueindex which is consisted of path index and value index, the index updating algorithm resolves XML updating problem when the XML document is updated, the XML index can be update at the same time.(2) Present a XML multiple branch pathes query algorithm DEPTHJOIN based on index. XML single path query methods and simple branch path query methods have been presented, but how to query multiple branch pathes have not been solved well. This paper presents the algorithm DEPTHJOIN for querying XML multiple branch pathes based on index. The algorithm encodes the XML document and creates the index for the XML documents. It restores the single paths of the multiple branch pathes using the multiple stacks on the process of matching of the query tree, judging the branch nodes have the same ancestors or parent or not by the index. Compared with the existing algorithms, the algorithm doesn't need join the single paths.(3) Propose an efficient algorithm MBPQ for XML multiple branch pathes query. The algorithm encodes the XML document and XML query tree, disjoints the multiple branch pathes into single paths, queries the singe paths and uses the stack to match the single pathes which have the same ancestors in the process of matching the single paths to the multiple branch pathes. Compared with the existing algorithms the algorithm makes full use of the typical of the multiple branch pathes, reduces the loop number extremely.(4) Develope a XML querying prototype system using VC++. Experiment results show that this system can run correctly.