Distributed Query Scheduling Techniques For Study

One of the key issues for query processing in distributed open environments is the query scheduling problem. Given a user query, after we know that there are n sources that are relevant to the answer of this query, the first issue we need to address is how to decompose the query into n subqueries, each targeting at one single source. The second issue is how to synchronize these n subqueries in the presence of inter-site joins. The third issue is how to package and assemble the results from n information sources according to the original query posed by the user.We have done a series of research of the question ,and have achieved Distributed Integration Mediation System (DIMS). We have resolved the first two questions in the context of DIMS. This thesis includes the following contents:1. Introduction of DIMS.2. Researching of metadata model (DIMS-IDL/IQL).3. Researching of distributed interoperable query scheduling framework.4. Researching of distributed interoperable query scheduling and optimizing technology.