Validation of mappings between schemas

摘要

Mappings between schemas are key elements in several contexts such as data exchange, data integration and peer data management systems. In all these contexts, the mapping design process requires the participation of a mapping designer, who needs to be able to validate the mapping that is being defined, i.e., check whether the mapping is in fact what the designer intended. However, to date very little work has directly focused on the effective validation of schema mappings. In this paper, we present a new approach for validating schema mappings that allows the mapping designer to ask whether they have certain desirable properties. We consider four properties of mappings: mapping satisfiability, mapping inference, query answerability and mapping losslessness. We reformulate these properties in terms of the problem of checking whether a query is lively over a database schema. A query is lively if there is a consistent instance of the database for which the query gives a non-empty answer. To show the feasibility of our approach, we use an implementation of the CQC method and provide some experimental results.