Allocca, Carlo; Costabile, Roberta; Fiorentino, Alessio; Perri, Simona; Zangari, Jessica Memory-saving evaluation plans for Datalog. (English) Zbl 1525.68182 Calimeri, Francesco (ed.) et al., Logics in artificial intelligence. 16th European conference, JELIA 2019, Rende, Italy, May 7–11, 2019. Proceedings. Cham: Springer. Lect. Notes Comput. Sci. 11468, 453-461 (2019). Summary: Ontology-based query answering (OBQA), without any doubt, represents one of the fundamental reasoning services in Semantic Web applications. Specifically, OBQA is the task of evaluating a (conjunctive) query over a knowledge base (KB) consisting of an extensional dataset paired with an ontology. A number of effective practical approaches proposed in the literature rewrite the query and the ontology into an equivalent Datalog program. In case of very large datasets, however, classical approaches for evaluating such programs tend to be memory consuming, and may even slow down the computation. In this paper, we explain how to compute a memory-saving evaluation plan consisting of an optimal indexing schema for the dataset together with a suitable body-ordering for each Datalog rule. To evaluate the quality of our approach, we compare our plans with the classical approach used by DLV over widely used ontological benchmarks. The results confirm the memory usage can be significantly reduced without paying any cost in efficiency.For the entire collection see [Zbl 1412.68007]. Cited in 1 Document MSC: 68T30 Knowledge representation 68N17 Logic programming 68P15 Database theory Keywords:Datalog; query answering; ontologies; query-plan; data indexing PDFBibTeX XMLCite \textit{C. Allocca} et al., Lect. Notes Comput. Sci. 11468, 453--461 (2019; Zbl 1525.68182) Full Text: DOI