The Research Of Rewriting XML Queries Based On Materialized Views

XML documents emerging in large numbers, how to effectively manage and query XML data has become a problem worthy of study.In order to integrate the needs of the database development, we studied storage and query XML documents based on the technology of Materialized View and query rewriting in Relational Database. The technology of query rewriting based on Materialized View is an important technology in query optimization field, that using result of stored view answer new query, can significantly improve query efficiency. Because the part of the new query needed can have been included in the calculation of the outcome of view, it does not require query accessing to the source database, which can save time of the query processing.By researching on basic theory of Materialized View, the view cache, query rewriting, we analysis on the advantages and disadvantages of Materialized View and Query Rewriting in existing result, on this basis, we Discuss how to use the Materialized View which is cached in relational database to answer query, and gives a system framework about XML query based on materialized view. In order to solve the issue of the existence of rewriting, in the system, we use the pattern matching algorithm, through the result of this algorithm, we can determine whether we can construct the compensation expression, through the algorithm of constructing the compensation expression, we can get the results of rewriting, through cached View in the database, we can complete the query. This system is designed into three modules, which are Pretreatment module, Query Transformation module and View Management module.