Abstract
The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach for finding contained rewritings of unions of conjunctive queries with arbitrary built-in predicates. Our approach is based on an improved method for testing conjunctive query containment in this context. Although conceptually simple, our approach generalizes previous methods for finding contained rewritings of conjunctive queries and is more powerful in the sense that many rewritings that can not be found using existing methods can be found by our approach. Furthermore, implication constraints (Zhang, X., & Ozsoyoglu, Z.M. (1997). Implication and referential constraints: A new formal resaoning. IEEE TKDE, 9(6):894–910, Now/Dec.) over the base relations can be easily handled. We then present a simplified approach which is less complete, but is much faster than the general approach, and it still finds maximum rewritings in several special cases. Our general approach finds more rewritings than previous algorithms such as the Bucket and the resolution-based algorithms. Our simplified approach generalizes the U-join and the MiniCon algorithms with no loss of efficiency.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Abiteboul, S., & Duschka, O. (1998). Complexity of answering queries using materalized views. In Proc. of PODS, pages 254–263.
Afrati, F. N., Li, C., & Mitra, P. Answering queries using views with arithmetic comparisons. In Proceedings of PODS’02, Madison, Wisconsin, USA, pages 209–220 (3–5 June).
Duschka, O. M., & Genesereth, M. R. (1997). Answering recursive queries using views. In Proc. 16th PODS, pages 109–116.
Duschka, O. M., Genesereth, M., & Levy, A. (2000). Recursive query plans for data integration. Journal of Logic Programming, special issue on Logic Based Heterogeneous Information Systems, pages 778–784.
Grant, J., & Minker, J. (2002). A logic-based approach to data intergration. Theory Pract. of Log. Prog. 2(3): 323–368.
Gryz, J. (1999). Query rewriting using views in the presence of functional and inclusion dependencies. Inf. Syst. 24(7): 597–612.
Halevy, A. Y. (2001). Answering queries using views: A survey. VLDB J. 10(4): 270–294.
Klug, A. C. (1988) On conjunctive queries containing inequalities. J. ACM 35(1): 146–160.
Lassez, J. L., & McAloon, K. (1992). A canonical form for generalized linear constraints. J. Symb. Comput. 13(1): 1–24 (January).
Levy, A., Rajaraman, A., & Ordille, J. J. (1996). Querying heterogeneous information sources using source descriptions. In Proc. of VLDB, pages 251–262.
Maher, M. J. (1993). A logic programming view of CLP. In Proc. 10th International Conference on Logic Programming, pages 737–753.
Mitra, P. (2001). An algorithm for answering queries efficiently using views. In Proc. of the 12th Australasian database conference.
Pottinger, R., & Halevy, A. Y. (2001). Minicon: A scalable algorithm for answering queries using views. VLDB J. 10(2–3): 182–198.
Qian, X. (1996). Query folding. In Proc. of 12th ICDE, pages 48–55.
Ullman, J. D. (1988). Principles of Database and Knowledge-Based Systems, vol. 1 & 2, 1st edition. Computer Science Press.
Ullman, J. D. (2000). Information integration using logical views. Theor. Comput. Sci. 239(2): 189–210.
Zhang, X., & Ozsoyoglu, Z. M. (1997). Implication and referential constraints: A new formal resaoning. IEEE TKDE 9(6): 894–910 (Nov/Dec).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Wang, J., Topor, R. & Maher, M. Rewriting Union Queries Using Views. Constraints 10, 219–251 (2005). https://doi.org/10.1007/s10601-005-2238-x
Issue Date:
DOI: https://doi.org/10.1007/s10601-005-2238-x