creators_name: Wu, Huayu creators_name: Wang Ling, Tok creators_name: Xu, Liang creators_name: Bao, Zhifeng type: conference_item datestamp: 2009-04-06 19:11:39 lastmod: 2009-04-14 04:37:10 metadata_visibility: show title: Performing Grouping and Aggregate Functions in XML Queries ispublished: pub full_text_status: public pres_type: paper abstract: Since more and more business data are represented in XML format, there is a compelling need of supporting analytical operations in XML queries. Particularly, the latest version of XQuery proposed by W3C, XQuery 1.1, introduces a new construct to explicitly express grouping operation in FLWOR expression. Existing works in XML query processing mainly focus on physically matching query structure over XML document. Given the explicit grouping operation in a query, how to efficiently compute grouping and aggregate functions over XML document is not well studied yet. In this paper, we extend our previous XML query processing algorithm, VERT, to efficiently perform grouping and aggregate function in queries. The main technique of our approach is introducing relational tables to index values. Query pattern matching and aggregation computing are both conducted with table indices. We also propose two semantic optimizations to further improve the query performance. Finally we present experimental results to validate the efficiency of our approach, over other existing approaches. date: 2009-04 pagerange: 1001-1001 event_title: 18th International World Wide Web Conference event_location: Madrid, Spain event_dates: April 20th-24th, 2009 event_type: conference refereed: TRUE citation: Wu, Huayu and Wang Ling, Tok and Xu, Liang and Bao, Zhifeng (2009) Performing Grouping and Aggregate Functions in XML Queries. In: 18th International World Wide Web Conference, April 20th-24th, 2009, Madrid, Spain. document_url: http://www2009.eprints.org/101/1/p1001.pdf