Query rewriting using views in a typed mediator environment.
|Author(s): || Kalinichenko L. A., Martynov D.O., Stupnikov S.A.
|Published:||Formal Methods and Models for Compositional Infrastuctures of Distributed Information Systems: The Systems and Means of Informatics, Special Issue. -- Moscow: IPI RAN, 2005. -- P. 152--182. (In Russian)
| Query rewriting method is proposed for the heterogeneous information
integration infrastructure formed by the subject mediator environment.
Local as View (LAV) approach treating schemata exported by sources as
materialized views over virtual classes of the mediator is considered
as the basis for the subject mediation infrastructure. In spite of
significant progress of query rewriting with views, it remains unclear
how to rewrite queries in the typed, object-oriented mediator
environment. This paper embeds conjunctive views and queries into an
advanced canonical object model of the mediator. The "selection-
projection-join" (SPJ) conjunctive query semantics based on type
specification calculus is introduced. The paper demonstrates how the
existing query rewriting approaches can be extended to be applicable
in such typed environment. The paper shows that refinement of the
mediator class instance types by the source class instance types is
the basic relationship required for establishing query containment in
the object environment.
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