Extends PDIS 96. It also extends the Capabilities Based Rewriting algorithm with the appropriate hooks for cost optimization and describes what plan pruning may be performed without losing the CBR's completeness. Finally it compares the CBR architecture with a real CBR-enhanced optimizer that was developed for Garlic. A mediator has to make sure that the queries that it sends to the sources are supported by them. Furthermore, the mediator has to leverage as much as possible on the source query capabilities.
Mediators fuse information from multiple heterogeneous information sources.
In the process they remove redundancies and resolve inconsistencies. Stanford University Thesis , 1997. Paper saving condensed version . S. Adali, S. Candan, Y. Papakonstantinou, V.S. Subrahmanyan. Y. Papakonstantinou, H. Garcia-Molina, J. Ullman.