The Database Query Prototype Under The Grid Environment

With the development of the grid technology, the concept data grid appears after the concept computational grid as the demand of the data application. How to access the existed databases, provide a uniform interface to access the databases, and compose the existed databases to make a virtual database is a issue that worth to study.The query function is used very frequently in the database application, the same to the grid environment. It appear frequently that compose the database that distribute in various computer nodes to make a virtual database dynamically to finish a query because of every database only include a part of the information. So, It is a question that how to finish the query and shorten the response time under the grid of high heterogeneity of the nodes and the widely various communication speed between the nodes.The prototype of database query under the grid environment studies how to access the relational databases that are distributed. It use the uniform data format (XML document) to express and transfer data, divide the system to a few module and communicate each other by the Grid Service technology. Hiding the heterogeneity by division of the interface and the implementation, it makes virtual database that is composed of various databases dynamically possible. And it presents a query plan generation and execution algorithm by reference of the parallel database and the distributed database technology. The prototype implement the SQL query of the virtual database that include nested query and can run on different database. The test shows that the design of the prototype is feasible.