Abstract

When data sources are integrated into a single global system, inconsistencies wrt global integrity constraints are likely to occur. In this paper, the notion of consistent answer to a global query in the context of the local-as-view model of data integration is characterized. Furthermore, a methodology for generating query plans for retrieving consistent answer to global queries is introduced. For this purpose, an extension of the inverse-rules algorithm for deriving query plans is presented. It can be used to answer first order queries posed to data sources integrated according to the local-as-view.

Citations