Using containment information for view evolution in dynamic distributed environments

Abstract

The maintenance of materialized views in large scale environments composed of numerous information sources (ISs), such as in the WWW, is complicated by ISs not only continuously modifying their contents bur also their capabilities (schemas and query interfaces). With current view technology, views become undefined when ISs change their capabilities. Our Evolvable View Environment (EVE) project addresses this new problem of evolving views under IS capabilities changes, which we call the view synchronization problem. Key principles of EVE include a user specified preference model for view evolution (Evolvable-SQL (E-SQL)) and a Model for Information Source Descriptions (MISD). We present a formal characterization of correctness of view synchronization using containment constraints defined in MISD. Then, we give a novel view synchronization algorithm for view rewriting, exploiting general containment constraints between the to-be-replaced relation and its replacement.