Research For XML Query Optimization Technology Based On Relational Database

With the rapid advancement of the web technology. The delivering and sharing of the information increases increasingly all over the world. The emergence of XML technique exactly deals with the above problem effectively. XML has become a standard for data expressing and a tool for information exchanging gradually, it will develop a new realm for the application of database.Because of the merits of relational-database, which includes mature technique, abroad application easy for expansion better interaction, abundance semantic, well formatted, well ability for control data, security, so we decide to choose store XML document to relational DB.This paper focuses on the technologies of path expression optimizing. The basic structural join is a core operation in XML query processing. This structural join algorithm is improved has realized the query optimization . The primary endeavor and contribution of this dissertation are as follows: By the use of the region coding and node model mapping method, an extended storage schema is presented for relational-database. We use breadth-first traverse XML tree, improving the structural join algorithms for processing parent/ child relationships; establishment of clustered index for the optional breadth traversal serial number of node coding, improving the structural join algorithms for processing preceding-sibling/ following-sibling relationships.The proposed methods have advantages of saving memory, shrinking the scanning area of list and remarkably improving the rate matching of lookup, they improve the efficiency of XML data query.