Abstract
While using an algebra that acts on sets of variable bindings for evaluating XML queries, the problem of constructing XML from these bindings arises. One approach is to define a powerful operator that is able to perform a complex construction of a representation of the XML result document. The drawback is that such an operator in its generality is hard to implement and disables algebraic optimization since it has to be executed last in the plan. Therefore we suggest to construct XML documents by special query execution plans called construction plans built from simple, easy to implement and efficient operators. The paper proposes four simple algebraic operators needed for XML document construction. Further, we introduce an optimizing translation algorithm of construction clauses into algebraic expressions and briefly point out algebraic optimizations enabled by our approach.
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References
S. Abiteboul, D. Quass, J. McHugh, J. Widom, and J. Wiener, “The Lorel query language for semistructured data,” Journal of Digital Libraries 1(1), 1996.
C. Beeri and Y. Tzaban, “SAL: An algebra for semistructured data and XML,” in Internat. Workshop on the Web and Databases, 1999, pp. 37-42.
T. Bray, J. Paoli, and C. M. Sperberg-McQueen, “Extensible Markup Language (XML) 1.0,” W3C recommendation, Technical Report, World Wide Web Consortium, February 1998.
M. J. Carey, D. Florescu, Z. G. Ives, Y. Lu, J. Shanmugasundaram, E.J. Shekita, and S.N. Subramanian, “XPERANTO: Publishing object-relational data as XML,” in Internat. Workshop on the Web and Databases, 2000, pp. 105-110.
D. Chamberlin, J. Clark, D. Florescu, J. Robie, J. Simeon, and M. Stefanescu, “Xquery 1.0: An XML query language,” W3C working draft, Technical Report, World Wide Web Consortium, June 2001.
V. Christophides, S. Cluet, and J. Simeon, “On wrapping query languages and efficient XML integration,” in Proc. of the ACM SIGMOD Conf. on Management of Data, 2000, pp. 141-152.
S. Cluet and G. Moerkotte, “Nested queries in object bases,” in Internat. Workshop on Database Programming Languages, 1993, pp. 226-242.
S. Cluet and G. Moerkotte, “Query processing in the schemaless and semistructured contex,” unpublished, 1996.
“DB2 XML Extender,” http://www-4.ibm.com/software/data/db2/extenders/xmlext/.
A. Deutsch, M. Fernandez, D. Florescu, A. Levy, and D. Suciu, “XML-QL: A query language for XML,” Technical Report, World Wide Web Consortium, http://www.w3.org/TR/NOTE-xml-ql, 1989.
D. Florescu and D. Kossmann, “Storing and querying XML data unsing an RDBMS,” IEEE Data Engineering Bulletin 22(3), 1999.
H. Garcia-Molina, J. D. Ullman, and J. Widom, Database System Implementation, Prentice-Hall, Englewood Cliffs, NJ, 2000.
G. Graefe, “Query evaluation techniques for large databases,” ACMS 25(2), 1993, 73-170.
A. Gupta, V. Harinarayan, and D. Quass, “Aggregate-query processing in data warehousing environments,” in Proc. of Internat. Conf. on Very Large Data Bases (VLDB), 1995, pp. 358-369.
C.-C. Kanne and G. Moerkotte, “Efficient storage of XML data,” in Proc. of IEEE Conf. on Data Engineering, 2000, p. 198.
R. Laddad, “XML APIs for databases,” http://www.javaworld.com/javaworld/jw-01-2000/jw-01-dbxml\_p.html, 2000.
M. Ley, “Databases & logic programming,” http://www.informatik.uni-trier.de/~ley/ db/index.html.
H. Liefke, “Horizontal query optimization on ordered semistructured data,” in Internat. Workshop on the Web and Databases, 1999, pp. 61-66.
D. Maier, “Database desiderata for an XML query language,” http://www.w3.org/TandS/QL/ QL98/pp/maier.html, 1998.
J. McHugh and J. Widom, “Query optimization for XML,” in Proc. of Internat. Conf. on Very Large Data Bases (VLDB), 1999, pp. 315-326.
D. Megginson, “Megginson technologies,” http://www.megginson.com/SAX/.
J. Robie, D. Chamberlin, and D. Florescu, “ Quilt: An XML query language for heterogeneous data sources,” in Internat. Workshop on the Web and Databases, 2000.
J. Robie, J. Lapp, and D. Schach, “XML query language (XQL),” http://www.w3.org/TandS/QL/ QL98/pp/xql.html, 1998.
J. Shanmugasundaram, R. Barr E. J. Shekita, M. J. Carey, B. G. Lindsay, H. Pirahesh, and B. Reinwald, “Efficiently publishing relational data as XML documents,” in Proc. of Internat. Conf. on Very Large Data Bases (VLDB), 2000, pp. 65-76.
J. Shanmugasundaram, K. Tufte, C. Zhang, G. He, D. J. DeWitt, and J. F. Naughton, “Relational databases for querying XML documents: Limitations and opportunities,” in Proc. of Internat. Conf. on Very Large Data Bases (VLDB), 1999, pp. 302-314.
D. E. Simmen, E. J. Shekita, and T. Malkemus, “Fundamental techniques for order optimization,” in Proc. of the ACM SIGMOD Conf. on Management of Data, 1996, pp. 57-67.
L. Wood et al., “Document Object Model (DOM) level 1 specification, version 1.0,” W3C recommendation, available at http://www.w3.org/TR/1998/REC-DOM-Level-1-19981001, October 1998.
M. Yoshikawa, T. Amagasa, T. Shimura, and S. Uemura, “XRel: A path-based approach to storage and retrieval of XML documents using relational databases,” ACM Transactions on Internet Technology 1(1), 2001.
“XML, XSLT and Oracle8i,” http://technet.oracle.com/sample_code/tech/xml/ xsql_servlet/sample_code_index.htm.
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Fiebig, T., Moerkotte, G. Algebraic XML Construction and its Optimization in Natix. World Wide Web 4, 167–187 (2001). https://doi.org/10.1023/A:1013831700817
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DOI: https://doi.org/10.1023/A:1013831700817