EXPRESS: a data EXtraction, Processing, and Restructuring System
ACM Transactions on Database Systems (TODS)
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
MiniCon: A scalable algorithm for answering queries using views
The VLDB Journal — The International Journal on Very Large Data Bases
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Data exchange: getting to the core
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2003
Clio grows up: from research prototype to industrial tool
Proceedings of the 2005 ACM SIGMOD international conference on Management of data
HePToX: marrying XML and heterogeneity in your P2P databases
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Data exchange: semantics and query answering
Theoretical Computer Science - Database theory
Nested mappings: schema mapping reloaded
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
Efficient core computation in data exchange
Journal of the ACM (JACM)
Towards a theory of schema-mapping optimization
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Structural characterizations of schema-mapping languages
Proceedings of the 12th International Conference on Database Theory
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
Static analysis of schema-mappings ensuring oblivious termination
Proceedings of the 13th International Conference on Database Theory
Scalable data exchange with functional dependencies
Proceedings of the VLDB Endowment
TRAMP: understanding the behavior of schema mappings through provenance
Proceedings of the VLDB Endowment
Normalization and optimization of schema mappings
The VLDB Journal — The International Journal on Very Large Data Bases
Leveraging query logs for schema mapping generation in U-MAP
Proceedings of the 2011 ACM SIGMOD International Conference on Management of data
Generating SPARQL executable mappings to integrate ontologies
ER'11 Proceedings of the 30th international conference on Conceptual modeling
Core schema mappings: Scalable core computations in data exchange
Information Systems
What is the IQ of your data transformation system?
Proceedings of the 21st ACM international conference on Information and knowledge management
Data exchange in datalog is mainly a matter of choice
Datalog 2.0'12 Proceedings of the Second international conference on Datalog in Academia and Industry
An update on query answering with restricted forms of negation
RR'12 Proceedings of the 6th international conference on Web Reasoning and Rule Systems
Data exchange with arithmetic operations
Proceedings of the 16th International Conference on Extending Database Technology
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A schema mapping is a declarative specification of the relationship between instances of a source schema and a target schema. The data exchange (or data translation) problem asks: given an instance over the source schema, materialize an instance (or solution) over the target schema that satisfies the schema mapping. In general, a given source instance may have numerous different solutions. Among all the solutions, universal solutions and core universal solutions have been singled out and extensively studied. A universal solution is a most general one and also represents the entire space of solutions, while a core universal solution is the smallest universal solution and is unique up to isomorphism (hence, we can talk about the core). The problem of designing efficient algorithms for computing the core has attracted considerable attention in recent years. In this paper, we present a method for directly computing the core by SQL queries, when schema mappings are specified by source-to-target tuple-generating dependencies (s-t tgds). Unlike prior methods that, given a source instance, first compute a target instance and then recursively minimize that instance to the core, our method avoids the construction of such intermediate instances. This is done by rewriting the schema mapping into a laconic schema mapping that is specified by first-order s-t tgds with a linear order in the active domain of the source instances. A laconic schema mapping has the property that a "direct translation" of the source instance according to the laconic schema mapping produces the core. Furthermore, a laconic schema mapping can be easily translated into SQL, hence it can be optimized and executed by a database system to produce the core. We also show that our results are optimal: the use of the linear order is inevitable and, in general, schema mappings with constraints over the target schema cannot be rewritten to a laconic schema mapping.