Authors: Bogdan Cautis Alin Deutsch Nicola Onose
Publish Date: 2010/10/05
Volume: 49, Issue: 2, Pages: 367-428
Abstract
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 parametersWe say that query Q is expressible by the program ensuremathmathcalP if it is equivalent to some expansion of ensuremathmathcalP Q is supported by ensuremathmathcalP if it has an equivalent rewriting using some finite set of ensuremathmathcalP’s expansions We present the first study of expressibility and support for sources that satisfy integrity constraints which is generally the case in practice
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