Query Processing in the SIMS Information Mediator

A critical problem in building an information mediator is how to translate a domain-level query into an efficient query plan for accessing the required data. We have built a flexible and efficient information mediator, called SIMS. This system takes a domain-level query and dynamically selects the appropriate information sources based on their content and availability, generates a query access plan that specifies the operations and their order for processing the data, and then performs semantic query optimization to minimize the overall execution time. This paper describes these three basic components of the query processing in SIMS.