Abstract
Currently, grouping in XQuery must be expressed implicitly with nested FLWOR expressions. With XQuery 1.1, an explicit group by clause will be part of this query language. As users integrate this new construct into their applications, it becomes important to have efficient evaluation techniques available to process even complex grouping conditions. Among them, the removal of distinct values or distinct nodes in the partitions defined by the group by clause is not well-supported yet. The evaluation technique proposed in this paper is able to handle duplicate removal in the partitions efficiently. Experiments show the superiority of our solution compared to state-of-the-art query processing.
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Beyer, K., Chamberlin, D., Colby, L., Özcan, F., Pirahesh, H., Xu, Y.: Extending XQuery for analytics. In: SIGMOD (2005)
Boag, S., Chamberlin, D., Fernández, M.F., Florescu, D., Robie, J., Siméon, J.: XQuery 1.0: An XML Query Language. W3C (2007)
Borkar, V., Carey, M.: Extending XQuery for grouping, duplicate elimination, and outer joins. In: XML 2004 (2004)
Charikar, M., Chaudhuri, S., Motwani, R., Narasayya, V.: Towards estimation error guarantees for distinct values. In: Proc. of the ACM PODS (2000)
Chaudhuri, S., Shim, K.: Including group-by in query optimization. In: Proc. VLDB (1994)
Engovatov, D.: XML Query 1.1 Requirements. W3C Working Draft (2007)
Fiebig, T., Helmer, S., Kanne, C-C., Moerkotte, G., Neumann, J., Schiele, R., Westmann, T.: Anatomy of a native XML base management system. j-VLDB-J 11(4) (2002)
Fiebig, T., Moerkotte, G.: Algebraic XML construction and its optimization in Natix. WWW Journal 4(3) (2001)
Gokhale, C., Gupta, N., Kumar, P., Lakshmanan, L., Ng, R., Prakash, B.A.: Complex group-by queries for XML. In: Proc. ICDE (2007)
Graefe, G.: Query evaluation techniques for large databases. ACM Computing Surveys 25(2) (1993)
Gupta, A., Harinarayan, V., Quass, D.: Aggregate-query processing in data warehousing environments. In: Proc. VLDB (1995)
Kay, M.: Positional grouping in XQuery. In: <XIME-P/> (2006)
May, N., Helmer, S., Moerkotte, G.: Strategies for query unnesting in XML databases. ACM TODS 31(3) (2006)
May, N., Moerkotte, G.: Main memory implementations for binary grouping. In: XSym (2005)
Paparizos, S., Al-Khalifa, S., Jagadish, H.V., Lakshmanan, L., Nierman, A., Srivastava, D., Wu, Y.: Grouping in XML. In: EDBT workshops (2002)
Re, C., Siméon, J., Fernández, M.F.: A complete and efficient algebraic compiler for XQuery. In: ICDE (2006)
Wiwatwattana, N., Jagadish, H.V., Lakshmanan, L., Srivastava, D.: X3: A cube operator for XML OLAP. In: Proc. ICDE (2007)
Yan, W.P., Larson, P.-Å.: Performing group-by before join. In: Proc. ICDE (1994)
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May, N., Moerkotte, G. (2007). Efficient XQuery Evaluation of Grouping Conditions with Duplicate Removals. In: Barbosa, D., Bonifati, A., Bellahsène, Z., Hunt, E., Unland, R. (eds) Database and XMLTechnologies. XSym 2007. Lecture Notes in Computer Science, vol 4704. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-75288-2_6
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DOI: https://doi.org/10.1007/978-3-540-75288-2_6
Publisher Name: Springer, Berlin, Heidelberg
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