Composing Local-As-View Mappings

Schema mapping composition is a fundamental operation in schema management and data exchange. The mapping composition problem has been extensively studied for a number of mapping languages, most notably source-to-target tuplegenerating dependencies (s-t tgds). An important class of s-t tgds are local-as-view (LAV) tgds. This class of mappings is prevalent in practical data integration and exchange systems, and recent work by ten Cate and Kolaitis shows that such mappings possess desirable structural properties. It is known that s-t tgds are not closed under composition. That is, given two mappings expressed with s-t tgds, their composition may not be definable by any set of s-t tgds (and, in general, may not be expressible in first-order logic). Despite their importance and extensive use in data integration and exchange systems, the closure properties of LAV composition remained open to date. The most important contribution of this paper is to show that LAV tgds are closed under com...

• Type: Journal
• Year: 2010
• Where: ICDT
• Authors: Patricia Arocena, Ariel Fuxman, Renee Miller
• Keywords: Database, ICDT 2010, Lav Mappings, Mapping Composition, S-t Tgds