Determining View dependencies using tableaux
ACM Transactions on Database Systems (TODS)
A vision for management of complex models
ACM SIGMOD Record
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
ILOG: Declarative Creation and Manipulation of Object Identifiers
VLDB '90 Proceedings of the 16th International Conference on Very Large Data Bases
Object Fusion in Mediator Systems
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Semantic adaptation of schema mappings when schemas evolve
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Data exchange: semantics and query answering
Theoretical Computer Science - Database theory
Composing schema mappings: Second-order dependencies to the rescue
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2004
Nested mappings: schema mapping reloaded
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
ACM Transactions on Database Systems (TODS)
Composition of mappings given by embedded dependencies
ACM Transactions on Database Systems (TODS)
ORCHESTRA: facilitating collaborative data sharing
Proceedings of the 2007 ACM SIGMOD international conference on Management of data
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Implementing mapping composition
The VLDB Journal — The International Journal on Very Large Data Bases
STBenchmark: towards a benchmark for mapping systems
Proceedings of the VLDB Endowment
Structural characterizations of schema-mapping languages
Proceedings of the 12th International Conference on Database Theory
Inverting schema mappings: bridging the gap between theory and practice
Proceedings of the VLDB Endowment
OpenII: an open source information integration toolkit
Proceedings of the 2010 ACM SIGMOD International Conference on Management of data
Second Order Quantifier Elimination: Foundations, Computational Aspects and Applications
Second Order Quantifier Elimination: Foundations, Computational Aspects and Applications
Scalable data exchange with functional dependencies
Proceedings of the VLDB Endowment
The complexity of evaluating tuple generating dependencies
Proceedings of the 14th International Conference on Database Theory
Data exchange and schema mappings in open and closed worlds
Journal of Computer and System Sciences
Designing and refining schema mappings via data examples
Proceedings of the 2011 ACM SIGMOD International Conference on Management of data
MapMerge: correlating independent schema mappings
The VLDB Journal — The International Journal on Very Large Data Bases
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The creation of values to represent incomplete information, often referred to as value invention, is central in data exchange. Within schema mappings, Skolem functions have long been used for value invention as they permit a precise representation of missing information. Recent work on a powerful mapping language called second-order tuple generating dependencies (SO tgds), has drawn attention to the fact that the use of arbitrary Skolem functions can have negative computational and programmatic properties in data exchange. In this paper, we present two techniques for understanding when the Skolem functions needed to represent the correct semantics of incomplete information are computationally well-behaved. Specifically, we consider when the Skolem functions in second-order (SO) mappings have a first-order (FO) semantics and are therefore programmatically and computationally more desirable for use in practice. Our first technique, linearization, significantly extends the Nash, Bernstein and Melnik unskolemization algorithm, by understanding when the sets of arguments of the Skolem functions in a mapping are related by set inclusion. We show that such a linear relationship leads to mappings that have FO semantics and are expressible in popular mapping languages including source-to-target tgds and nested tgds. Our second technique uses source semantics, specifically functional dependencies (including keys), to transform SO mappings into equivalent FO mappings. We show that our algorithms are applicable to a strictly larger class of mappings than previous approaches, but more importantly we present an extensive experimental evaluation that quantifies this difference (about 78% improvement) over an extensive schema mapping benchmark and illustrates the applicability of our results on real mappings.