Query rewriting for semistructured data
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
A framework for expressing and combining preferences
SIGMOD '00 Proceedings of the 2000 ACM SIGMOD international conference on Management of data
Minimization of tree pattern queries
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
XIRQL: a query language for information retrieval in XML documents
Proceedings of the 24th annual international ACM SIGIR conference on Research and development in information retrieval
Containment and equivalence for an XPath fragment
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
The Index-Based XXL Search Engine for Querying XML Data with Relevance Ranking
EDBT '02 Proceedings of the 8th International Conference on Extending Database Technology: Advances in Database Technology
Querying with Intrinsic Preferences
EDBT '02 Proceedings of the 8th International Conference on Extending Database Technology: Advances in Database Technology
Containment for XPath Fragments under DTD Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Through different eyes: assessing multiple conceptual views for querying web services
Proceedings of the 13th international World Wide Web conference on Alternate track papers & posters
Optimization of relational preference queries
ADC '05 Proceedings of the 16th Australasian database conference - Volume 39
Foundations of preferences in database systems
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Building an efficient preference XML query processor
Proceedings of the 2009 ACM symposium on Applied Computing
Relaxing queries based on XML structure and content preferences
WISS'10 Proceedings of the 2010 international conference on Web information systems engineering
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Efficient query processing using XPath or XQuery has inspired a lot of research. In contrast to classical exact match retrieval, in today's systems, specifying preferences rather than simple hard constraints is essential. As the structure of XML documents plays a major part in retrieval, recently approximate query matching on structure has received attention. However, query processing of structural user preferences has not yet been considered. In this paper we enable users to express structural preferences and consider the problem of optimizing XML twig queries while preserving the ordering induced on the result set by such user preferences. Evaluating such queries generally needs a rewriting into a set of queries, where each leaf node can be expanded by combinations of structural elements derived from the preference information. Since such structure expansions typically contain redundancies and the efficiency of query evaluation strongly depends on the size of the set of rewritten queries, it is important to identify and simplify necessary expansions. We give a detailed analysis of this process and present an optimization algorithm that determines a minimal set of queries, which in turn are minimal in their expanded nodes, while maintaining the ordering induced by the preference structure. Finally, we provide a comprehensive practical evaluation of our optimization against the XMark benchmark dataset.