Querying Data Sources that Export Infinite Sets ofViews

We study the problem of querying data sources that accept only a limited set of queries, such as sources accessible by Web services which can implement very large (potentially infinite) families of queries. We revisit a classical setting in which the application queries are conjunctive queries and t...

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Bibliographic Details
Published in:Theory of computing systems 2011-08, Vol.49 (2), p.367-428
Main Authors: Cautis, Bogdan, Deutsch, Alin, Onose, Nicola
Format: Article
Language:English
Subjects:
Data sources
Equivalence
Exports
Integrity
International trade
Mathematical analysis
Queries
Recursive
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Summary:We study the problem of querying data sources that accept only a limited set of queries, such as sources accessible by Web services which can implement very large (potentially infinite) families of queries. We revisit a classical setting in which the application queries are conjunctive queries and the source accepts families of conjunctive queries specified as the expansions of a (potentially recursive) Datalog program with parameters. We say that query Q is expressible by the program ensuremath P if it is equivalent to some expansion of ensuremath P . Q is supported by ensuremath P if it has an equivalent rewriting using some finite set of ensuremath P 's expansions. We present the first study of expressibility and support for sources that satisfy integrity constraints, which is generally the case in practice.
ISSN:1432-4350
1433-0490
DOI:10.1007/s00224-010-9293-4