Collaborative Research: The REVELATION Project Query Processing In Behavioral Object-Oriented Databases

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Many new data management systems are being developed to support applications with advanced data management requirements, such as extended relational models, persistent programming languages and object-oriented databases. Such systems enhance semantic expressiveness, but they must offer good performance to be viable commercial technologies. An area particularly needful of improved performance is query processing, where new modeling features such as encapsulation, type hierarchies, complex values and object identity make conventional set-processing methods difficult or ineffective to apply. The overall goal of the Revelation project is to expand query processing to address and exploit these new modeling extensions at all levels of query processing, from schema management, through optimization and physical planning, to runtime support. For encapsulation, a Revealer is incorporated, a trusted system component that can access type implementations. Heterogeneity in collections arising from subtyping and polymorphism is handled by an Annotater that reasons across schema definitions. Complex values and identity are addressed both at the logical algebra level, with new operations to deal with ordered structures such as sequences and arrays, and at the physical level with new operators such as one to assemble complex objects. This project will construct a prototype query processor, exploiting existing software technology such as the Volcano optimizer generator and the Volcano query evaluation system.