XRel: a path-based approach to storage and retrieval of XML documents using relational databases
ACM Transactions on Internet Technology (TOIT)
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
WISE '02 Proceedings of the 3rd International Conference on Web Information Systems Engineering
Selectivity Estimation for XML Twigs
ICDE '04 Proceedings of the 20th International Conference on Data Engineering
Full-Fledged Algebraic XPath Processing in Natix
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
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
Statistical learning techniques for costing XML queries
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Cost-based optimization in DB2 XML
IBM Systems Journal
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
Efficient structural joins on indexed XML documents
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Staircase join: teach a relational DBMS to watch its (axis) steps
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Cost based plan selection for xpath
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
A bi-labeling based XPath processing system
Information Systems
Improving the efficiency of XPath execution on relational systems
EDBT'06 Proceedings of the 10th international conference on Advances in Database Technology
Optimizing sorting and duplicate elimination in XQuery path expressions
DEXA'05 Proceedings of the 16th international conference on Database and Expert Systems Applications
A query optimization assistant for XPath
Proceedings of the 14th International Conference on Extending Database Technology
Optimizing XML twig queries with full-text predicates
ACM SIGMOD Record
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The creation of a generic and modular query optimization and processing infrastructure can provide significant benefits to XML data management. Key pieces of such an infrastructure are the physical operators that are available to the execution engine, to turn queries into execution plans. Such operators, to be efficient, need to implement sophisticated algorithms for logical XPath or XQuery operations. Moreover, to enable a cost-based optimizer to choose among them correctly, it is also necessary to provide cost models for such operator implementations. In this paper we present two novel families of algorithms for XPath physical operators, called LookUp (LU) and Sort-Merge-based (SM), along with detailed cost models. Our algorithms have significantly better performance compared to existing techniques over any one of a variety of different XML storage systems that provide a set of common primitive access methods. To substantiate the robustness and efficiency of our physical operators, we evaluate their individual performance over four different XML storage engines against operators that implement existing XPath processing techniques. We also demonstrate the performance gains for twig processing of using plans consisting of our operators compared to a state of the art holistic technique, specifically Twig2Stack. Additionally, we evaluate the precision of our cost models, and we conduct an analysis of the sensitivity of our algorithms and cost models to a variety of parameters.