It also defines partial order b,and on the basis of it the monotonicity of these operators,especially recursive query is discussed.

This paper describes formally recursive query with relational algebra and datalog rule based on logical, and also discusses the least-fixed point computation equation and the principle of stratified negation in recursive query.

The traditional method mainly focuses attention on a large number of queries on the XML data stream, which doesn’t meet the present need, so how to complete the recursive query over XML data stream is an urgent problem.

The Technique of Optimizing Structurally Recursive Queries by DTD;

Taking account of operators needs of CPU and disk I/O into account, we focus our research on processor allocation of parallel query on Shared Nothing execution environment.

In order to improve the performance and accuracy of user querying(refer to multi-heterogeneous data sources) in grid environment,the paper presents a parallel querying solution based on multi-ontology.

In this paper,a query complete-including method is proposed based on data stream sharing,and then it is optimized to a query combining method with its cost model.