Research On The Update Of XQuery Views

Modern data sources, including structural and semi-structural sources, often export XML views over base data to supply users with different XQuery views to query XML files safely and reliably. XML view includes materialized view and virtual view, which has similar merits like relational database view. But for the materialized view, there is a data refresh problem, that is when the XML source changes, how to refresh the materialized view. This is the key point of this paper.This paper introduces a Java API firstly, which can execute query and get results from query. Users can prepare XQuery search, kidnap XQuery search strings, and execute it. Furthmore, users can also creat XML views in Java application programs. Subsequently, it discusses the update operation of XML files. Modification ability for data is basic request of information storage. To make XML be the general data representation and sharing format, highly effective update function is indispensable.With the update of XML query specification, XQuery update specification gives the goals and requirements on February 11, 2005 and on January 27, 2006, XQuery Update Facility and XQuery Update Facility Use Cases are first released. The paper analyzes the challenges in maintaining XQuery Views and adopts an incremental maintenance framework for materialized view and gives a solution based on an algebraic update propagation strategy and on special semantic identifier. Our solution derives the same result with a very small overhead compared to re-computation. The algebraic update propagation strategy transforms updates to XML data into update primitives applied to the XAT data model and designed rules for each algebra node to propagate updates through the XAT tree up to the result view. Finally using deep union operator to fuse XML fragments based on special semantic identifier, which consists of three steps. First, we define how lineage and order information of processed XML data is encoded using the Context Schema. Second, we use the Context Schema to generate reproducible semantic ids for nodes in the XML result...