Skip to main content
Article thumbnail
Location of Repository

Scalable Containment for Unions of Conjunctive Queries under Constraints

By George Konstantinidism et al.


We consider the problem of query containment under ontological constraints, such as those of RDFS. Query containment, i.e., deciding whether the answers of a given query are always contained in the answers of another query, is an important problem to areas such as database theory and knowledge representation, with applications to data integration, query optimization and minimization. We consider unions of conjunctive queries, which constitute the core of structured query languages, such as SPARQL and SQL. We also consider ontological constraints or axioms, expressed in the language of Tuple-Generating Dependencies. TGDs capture RDF/S and fragments of Description Logics. We consider classes of TGDs for which the chase is known to terminate. Query containment under chase-terminating axioms can be decided by first running the chase on one of the two queries and then rely on classic relational containment. When considering unions of conjunctive queries, classic algorithms for both the chase and containment phases suffer from a large degree of redundancy. We leverage a graph-based modeling of rules, that represents multiple queries in a compact form, by exploiting shared patterns amongst them. As a result we couple the phases of both for chase and regular containment and end up with a faster and more scalable algorithm. Our experiments show a speedup of close to two orders of magnitude

Topics: Categories and Subject Descriptors H.2.3 [Database Management, Languages—Query Languages, H.2.4 [Database Management, Systems—Query processing General Terms Algorithms, Performance, Experimentation
Year: 2013
OAI identifier: oai:CiteSeerX.psu:
Provided by: CiteSeerX
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • (external link)
  • (external link)
  • Suggested articles

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.