2013/12/31 by Davide Martinenghi, Martinenghi, Davide
Computer Science · #Advanced Database Systems and Queries #Data Management and Algorithms #Databases (cs.DB) #FOS: Computer and information sciences #Semantic Web and Ontologies #cs.DB
paper · pdf · doi:10.48550/arxiv.1401.0069
2 pages, 0 figures
openalex publication_date 2013/12/31 · arxiv created 2014/01/03 · arxiv updated 2014/01/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Access limitations are restrictions in the way in which the tuples of a relation can be accessed. Under access limitations, query answering becomes more complex than in the traditional case, with no guarantee that the answer tuples that can be extracted (aka maximal answer) are all those that would be found without access limitations (aka complete answer). The field of query answering under access limitations has been broadly investigated in the past. Attention has been devoted to the problem of determining relations that are relevant for a query, i.e., those (possibly off-query) relations that might need to be accessed in order to find all tuples in the maximal answer. In this short paper, we show that relevance is undecidable for Datalog queries.