Normalization and optimization of schema mappings

Schema mappings are high-level specifications that describe the relationship between two database schemas. They are an important tool in several areas of database research, notably in data integration and data exchange. However, a concrete theory of schema mapping optimization including the formulation of optimality criteria and the construction of algorithms for computing optimal schema mappings is completely lacking to date. The goal of this work is to fill this gap. We start by presenting a system of rewrite rules to minimize sets of source-to-target tuple-generating dependencies (st-tgds, for short). Moreover, we show that the result of this minimization is unique up to variable renaming. Hence, our optimization also yields a schema mapping normalization. By appropriately extending our rewrite rule system, we also provide a normalization of schema mappings containing equality-generating targetdependencies (egds). An important application of such a normalization is in the area of...

• Type: Journal
• Year: 2011
• Where: VLDB
• Authors: Georg Gottlob, Reinhard Pichler, Vadim Savenkov
• Keywords: Concrete Syntactic Representation, Database, Query Answering, Schema Mappings, VLDB 2011