Monadic Datalog Containment

  • Michael Benedikt
  • Pierre Bourhis
  • Pierre Senellart
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7392)

Abstract

We reconsider the problem of containment of monadic datalog (MDL) queries in unions of conjunctive queries (UCQs). Prior work has dealt with special cases, but has left the precise complexity characterization open. We begin by establishing a 2EXPTIME lower bound on the MDL/UCQ containment problem, resolving an open problem from the early 90’s. We then present a general approach for getting tighter bounds on the complexity, based on analysis of the number of mappings of queries into tree-like instances. We use the machinery to present an important case of the MDL/UCQ containment problem that is in co-NEXPTIME, and a case that is in EXPTIME. We then show that the technique can be used to get a new tight upper bound for containment of tree automata in UCQs. We show that the new MDL/UCQ upper bounds are tight.

Keywords

Access Method Conjunctive Query Tree Automaton Tree Pattern Query Datalog Program 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Shmueli, O.: Equivalence of datalog queries is undecidable. J. Log. Prog. 15(3) (1993)Google Scholar
  2. 2.
    Bonatti, P.A.: On the decidability of containment of recursive datalog queries. In: PODS (2004)Google Scholar
  3. 3.
    Calvanese, D., De Giacomo, G., Vardi, M.Y.: Decidable containment of recursive queries. Theoretical Computer Science 336(1) (2005)Google Scholar
  4. 4.
    Chaudhuri, S., Vardi, M.Y.: On the equivalence of recursive and nonrecursive Datalog programs. In: PODS (1992)Google Scholar
  5. 5.
    Chaudhuri, S., Vardi, M.Y.: On the equivalence of recursive and nonrecursive Datalog programs. JCSS 54(1) (1997)Google Scholar
  6. 6.
    Cosmadakis, S.S., Gaifman, H., Kanellakis, P.C., Vardi, M.Y.: Decidable optimization problems for database logic programs. In: STOC (1988)Google Scholar
  7. 7.
    Chaudhuri, S., Vardi, M.Y.: On the complexity of equivalence between recursive and nonrecursive Datalog programs. In: PODS (1994)Google Scholar
  8. 8.
    Calì, A., Martinenghi, D.: Conjunctive Query Containment under Access Limitations. In: Li, Q., Spaccapietra, S., Yu, E., Olivé, A. (eds.) ER 2008. LNCS, vol. 5231, pp. 326–340. Springer, Heidelberg (2008)CrossRefGoogle Scholar
  9. 9.
    Benedikt, M., Gottlob, G., Senellart, P.: Determining relevance of accesses at runtime. In: PODS (2011)Google Scholar
  10. 10.
    Calvanese, D., Giacomo, G.D., Lenzerini, M., Vardi, M.Y.: Containment of conjunctive regular path queries with inverse. In: KR (2000)Google Scholar
  11. 11.
    Courcelle, B.: Recursive queries and context-free graph grammars. Theoretical Computer Science 78(1) (1991)Google Scholar
  12. 12.
    ten Cate, B., Segoufin, L.: Unary negation. In: STACS (2011)Google Scholar
  13. 13.
    Benedikt, M., Bourhis, P., Ley, C.: Querying schemas with access paths. PVLDB (2012)Google Scholar
  14. 14.
    Björklund, H., Martens, W., Schwentick, T.: Optimizing Conjunctive Queries over Trees Using Schema Information. In: Ochmański, E., Tyszkiewicz, J. (eds.) MFCS 2008. LNCS, vol. 5162, pp. 132–143. Springer, Heidelberg (2008)CrossRefGoogle Scholar
  15. 15.
    Rajaraman, A., Sagiv, Y., Ullman, J.D.: Answering queries using templates with binding patterns. In: PODS (1995)Google Scholar
  16. 16.
    Li, C., Chang, E.Y.: Answering queries with useful bindings. ACM TODS 26(3) (2001)Google Scholar
  17. 17.
    Calì, A., Martinenghi, D.: Querying the deep web. In: EDBT (2010)Google Scholar
  18. 18.
    Björklund, H., Martens, W., Schwentick, T.: Validity of tree pattern queries with respect to schema information (2012) (unpublished draft)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Michael Benedikt
    • 1
  • Pierre Bourhis
    • 1
  • Pierre Senellart
    • 2
  1. 1.Oxford UniversityOxfordUnited Kingdom
  2. 2.Institut Mines–Télécom; Télécom ParisTech; CNRS LTCIParisFrance

Personalised recommendations