Composition of mappings given by embedded dependencies

Composition of mappings between schemas is essential to support schema evolution, data exchange, data integration, and other data management tasks. In many applications, mappings are given by embedded dependencies. In this paper, we study the issues involved in composing such mappings. Our algorithms and results extend those of Fagin et al. [8] who studied composition of mappings given by several kinds of constraints. In particular, they proved that full source-to-target tuplegenerating dependencies (tgds) are closed under composition, but embedded source-to-target tgds are not. They introduced a class of second-order constraints, SO tgds, that is closed under composition and has desirable properties for data exchange. We study constraints that need not be source-to-target and we concentrate on obtaining (first-order) embedded dependencies. As part of this study, we also consider full dependencies and secondorder constraints that arise from Skolemizing embedded dependencies. For each ...

• Type: Conference
• Year: 2005
• Where: PODS
• Authors: Alan Nash, Philip A. Bernstein, Sergey Melnik
• Keywords: Database, Embedded Dependencies, PODS 2005, Second-order Dependencies, Source-to-target Tuplegenerating Dependencies