On supporting containment queries in relational database management systems
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Statistical synopses for graph-structured XML databases
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
Estimating Answer Sizes for XML Queries
EDBT '02 Proceedings of the 8th International Conference on Extending Database Technology: Advances in Database Technology
Counting Twig Matches in a Tree
Proceedings of the 17th International Conference on Data Engineering
Estimating the Selectivity of XML Path Expressions for Internet Scale Applications
Proceedings of the 27th International Conference on Very Large Data Bases
Indexing and Querying XML Data for Regular Path Expressions
Proceedings of the 27th International Conference on Very Large Data Bases
The VLDB Journal — The International Journal on Very Large Data Bases
The XML benchmark project
Containment join size estimation: models and methods
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Structural Joins: A Primitive for Efficient XML Query Pattern Matching
ICDE '02 Proceedings of the 18th International Conference on Data Engineering
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As XML has become the de facto standard for data presentation and exchanging on the Web, XML query optimization has emerged as an important research issue. It is widely accepted that structural joins, which evaluate the containment (ancestor-descendant) relationships between XML elements, are important to the XML query processing. Estimating structural join size accurately and quickly thus becomes crucial to the success of XML query plan selection. In this paper, we propose to apply Cosine transform to structural join size estimation. Our approach captures structural information of XML data using mathematical functions, which are then approximated by the Cosine series. We derive a simple formula to estimate the structural join size using the Cosine series. Theoretical analyses and extensive experiments have been performed. The experimental results show that, compared with state-of-the-art IM-DA-Est method, our method is several order faster, requires less memory, and yields better or comparable estimates.