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We investigate the data exchange from relational databases to RDF graphsinspired by R2RML with the addition of target shape schemas. We study theproblems of consistency i.e., checking that every source instance admits asolution, and certain query answering i.e., finding answers present in everysolution. We identify the class of constructive relational to RDF data exchangethat uses IRI constructors and full tgds (with no existential variables) in itssource to target dependencies. We show that the consistency problem iscoNP-complete. We introduce the notion of universal simulation solution thatallows to compute certain query answers to any class of queries that is robustunder simulation. One such class are nested regular expressions (NREs) that areforward i.e., do not use the inverse operation. Using universal simulationsolution renders tractable the computation of certain answers to forward NREs(data-complexity). Finally, we present a number of results that show thatrelaxing the restrictions of the proposed framework leads to an increase incomplexity.

Consistency and Certain Answers in Relational to RDF Data Exchange with Shape Constraints