D. Calvanese
G. De Giacomo
M. Y. Vardi
Abstract
Current information systems are required to deal with more complex data with respect to traditional relational data. The database community has already proposed abstractions for these kinds of data, in particular in terms of semistructured data models. A semistructured model conceives a database essentially as a finite directed labeled graph whose nodes represent objects, and whose edges represent relationships between objects. In the same way as conjunctive queries form the core of any query language for the relational model, regular path queries (RPQs) and their variants are considered the basic querying mechanisms for semistructured data.Besides the basic task of query answering, i.e., evaluating a query over a database, databases should support other reasoning services related to querying. One of the most important is query containment, i.e., verifying whether for all databases the answer to a query is a subset of the answer to a second query. Another important reasoning service that has received considerable attention in the recent years is view-based query processing, which amounts to processing queries based on a set of materialized views, rather than on the raw data in the database.The goal of this paper is to describe basic results and techniques concerning query containment and view based query processing for the class of two-way regular-path queries (which extend RPQs with the inverse operator). We will demonstrate that the basic services for reasoning about two way regular path queries are decidable, thus showing that the limited form of recursion expressible by these queries does not endanger the decidability of reasoning. Besides the specific results, our methods show the power of two-way automata in reasoning on complex queries.
- S. Abiteboul, P. Buneman, and D. Suciu. Data on the Web: from Relations to Semistructured Data and XML. Morgan Kaufmann, 2000.]] Google Scholar
Digital Library
- S. Abiteboul and O. Duschka. Complexity of answering queries using materialized views. In Proc. of PODS'98, pages 254--265, 1998.]] Google ScholarDigital Library
- S. Abiteboul and V. Vianu. Regular path queries with constraints. J. of Computer and System Sciences, 58(3):428--452, 1999.]] Google ScholarDigital Library
- S. Adali, K. S. Candan, Y. Papakonstantinou, and V. S. Subrahmanian. Query caching and optimization in distributed mediator systems. In Proc. of ACM SIGMOD, pages 137--148, 1996.]] Google ScholarDigital Library
- A. V. Aho, Y. Sagiv, and J. D. Ullman. Equivalence among relational expressions. SIAM J. on Computing, 8:218--246, 1979.]]Google ScholarDigital Library
- S. Boag, D. Chamberlin, M. F. Fernandez, D. Florescu, J. Robie, and J. Simeon. XQuery 1.0: An XML query language w3c working draft. Technical report, World Wide Web Consortium, Aug. 2003. Available at http://www.w3.org/TR/xquery.]]Google Scholar
- P. Buneman. Semistructured data. In Proc. of PODS'97, pages 117--121, 1997.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, D. Nardi, and R. Rosati. Description logic framework for information integration. In. Proc. of KR'98, page 2--13, 1998.]]Google Scholar
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. Rewriting of regular expressions and regular path queries. In Proc. of PODS'99, pages 194--204, 1999.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. Containment of conjunctive regular path queries with inverse. In Proc. of KR 2000, pages 176--185, 2000.]]Google Scholar
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. Query processing using views for regular path queries with inverse. In Proc. of PODS 2000, pages 58--66, 2000.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. View-based query processing and constraint satisfaction. In Proc. of LICS 2000, pages 361--371, 2000.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. What is query rewriting? In Proc. of KRDB 2000, pages 17--27. CEUR Electronic Workshop Proceedings, http://ceur-ws.org/Vol-29/, 2000.]]Google ScholarCross Ref
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. View-based query answering and query containment over semistructured data. In Proc. of DBPL 2001, 2001.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. Lossless regular views. In Proc. of PODS 2002, pages 58--66, 2002.]] Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. Rewriting of regular expressions and regular path queries. J. of Computer and System Sciences, 64(3): 443--465, 2002. Extended and revised version of {9}.]]Google ScholarDigital Library
- D. Calvanese, G. De Giacomo, M. Lenzerini, and M. Y. Vardi. View-based query containment. In Proc. of PODS 2003, pages 56--67, 2003.]] Google ScholarDigital Library
- A. K. Chandra and P. M. Merlin. Optimal implementation of conjunctive queries in relational data bases. In Proc. of STOC'77, pages 77--90, 1977.]] Google ScholarDigital Library
- S. Chaudhuri, S. Krishnamurthy, S. Potarnianos, and K. Shim. Optimizing queries with materialized views. In Proc. of ICDE'95, 1995.]] Google ScholarDigital Library
- J. Clark and S. DeRose. XML path Language (XPath) version 1.0- W3C recommendation 16 november 1999. Technical report, World Wide Web Consortium, 1999. Available at http://www.w3.org/TR/1999/REC-xpath-19991116.]]Google Scholar
- A. Deutsch and V. Tannen. Optimization properties for classes of conjunctive regular path queries. In Proc. of DBPL 2001, 2001.]] Google ScholarDigital Library
- T. Feder and M. Y. Vardi. The computational structure of monotone monadic SNP and constraint satisfaction. SIAM J. on Computing, 28:57--104, 1999.]] Google ScholarDigital Library
- M. Friedman, A. Levy, and T. Millstein. Navigational plans for data integration. In Proc. of AAAI'99, pages 67--73. AAAI Press/The MIT Press, 1999.]] Google ScholarDigital Library
- M. R. Garey and D. S. Johnson. Computers and Intractability ---A guide to NP -completeness. W. H. Freeman and Company, San Francisco (CA, USA), 1979.]] Google ScholarDigital Library
- G. Grahne and A. O. Mendelzon. Tableau techniques for querying information sources through global schemas. In Proc. of ICDT'99, volume 1540 of LNCS, pages 332--347. Springer, 1999.]] Google ScholarDigital Library
- G. Grahne and A. Thomo. Query containment and rewriting using view for regular path queries under constraints. In Proc. of PODS 2003, pages 111--122, 2003.]] Google ScholarDigital Library
- A. Gupta and J. D. Ullman. Generalizing conjunctive query containment for view maintenance and integrity constraint verifi cation (abstract). In Workshop on Deductive Databases (In conjunction with JICSLP), page 195, Washington D.C. (USA), 1992.]]Google Scholar
- A. Y. Halevy. Theory of answering queries using views. SIGMOD Record, 29(4):40--47, 2000.]] Google ScholarDigital Library
- A. Y. Halevy. Answering queries using views: A survey. VLDB Journal, 10(4):270--294, 2001.]] Google ScholarDigital Library
- J. E. Hopcroft and J. D. Ullman. Introduction to Automata Theory, Languages, and Computation. Addison Wesley Publ. Co. 1979.]] Google ScholarDigital Library
- A. C. Klug. On conjunctive queries containing inequalities. J. of the ACM, 35(1): 146--160, 1988.]] Google ScholarDigital Library
- M. Lenzerini. Data integration: A theoretical perspective. In Proc. of PODS 2002, pages 233--246, 2002.]] Google ScholarDigital Library
- A. Y. Levy, A. O. Mendelzon, Y. Sagiv, and D. Srivastava. Answering queries using views. In Proc. of PODS'95, pages 95--104, 1995.]] Google ScholarDigital Library
- A. Y. Levy and M.-C. Rousset. Verification of knowledge bases: a unifying logical view. In Proc. of the 4th European Symposium on the Validation and Verification of Knowledge Based Systems, Leuven, Belgium, 1997.]]Google Scholar
- A. Y. Levy and Y. Sagiv. Semantic query optimization in Datalog program. In Proc. of PODS'95, pages 163--173, 1995.]] Google ScholarDigital Library
- A. R. Meyer and L. J. Stockmeyer. The equivalence problem for regular expressions with squaring requires exponential time. In Proc. of the 13th IEEE Symp. on Switching and Automata Theory, pages 125--129, 1972.]]Google ScholarDigital Library
- T. D. Millstein, A. Y. Levy, and M. Friedman. Query containment for data integration systems. In Proc. of PODS 2000, pages 67--75, 2000.]] Google ScholarDigital Library
- A. Motro. Panorama: A database system that annotates its answers to queries with their properties. J of Intelligent Information Systems, 7(1), 1996.]] Google ScholarDigital Library
- Y. Sagiv and M. Yannakakis. Equivalences among relational expressions with the union and difference operators. J. of the ACM, 27(4):633--655, 1980.]] Google ScholarDigital Library
- W. J. Savitch. Relationship between nondeterministic and deterministic tape complexities. J. of Computer and System Sciences, 4:177--192, 1970.]]Google ScholarDigital Library
- O. Shmueli. Equivalence of Datalog queries is undecidable. J. of Logic Programming, 15(3):231--241, 1993.]] Google ScholarDigital Library
- J. D. Ullman. Information integration using logical views. In Proc. of ICDT'97, volume 1186 of LNCS, pages 19--40. Springer, 1997.]] Google ScholarDigital Library
- R. van der Meyden. The Complexity of Querying Indefinite Information. PhD thesis, Rutgers University, 1992.]] Google ScholarDigital Library
- M. Y. Vardi. The complexity of relational query languages. In Proc. of STOC'82, pages 137--146, 1982.]] Google ScholarDigital Library
- M. Y. Vardi. A temporal fi xpoint calculus. In Proc. of POPL'88, pages 250--259, San Diego (CA, USA), 1988.]] Google ScholarDigital Library
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