Storing and querying ordered XML using a relational database system
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Holistic twig joins: optimal XML pattern matching
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
EDBT '02 Proceedings of the Worshops XMLDM, MDDE, and YRWS on XML-Based Data Management and Multimedia Engineering-Revised Papers
From region encoding to extended dewey: on efficient processing of XML twig pattern matching
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Twig2Stack: bottom-up processing of generalized-tree-pattern queries over XML documents
VLDB '06 Proceedings of the 32nd international conference on Very large data bases
Twiglist: make twig pattern matching fast
DASFAA'07 Proceedings of the 12th international conference on Database systems for advanced applications
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More and more XML data have been generated and used in the data exchange. XML employs a tree-structure data model, but lots of queries submitted by users are not like the tree-structure. Those queries contain ancestor axis in predicates, and specify the pattern of selection predicates on multiple elements from descendants to ancestors. Efficiently finding all occurrences of such an xtwig pattern in an XML database is crucial for XML query processing. A straightforward method is to rewrite an xtwig pattern to equivalent reverse-axis-free one. However, this method needs scanning the element streams several times and is rather expensive to evaluate. In this paper, we study the xtwig pattern, and propose two basic decomposing methods, VertiDec and HoriDec, and a holistic processing method, XtwigStack, for processing xtwig queries. The experiments show that the holistic algorithm is much more efficient than the rewriting and decomposition approaches.