Stream processing of XPath queries with predicates
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Semantic query optimization for XQuery over XML streams
VLDB '05 Proceedings of the 31st international conference on Very large data bases
Query optimization in XML structured-document databases
The VLDB Journal — The International Journal on Very Large Data Bases
Taming XPath queries by minimizing wildcard steps
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Semantic query optimization in an automata-algebra combined XQuery engine over XML streams
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Towards performance efficiency in safe XML update
WISE'07 Proceedings of the 8th international conference on Web information systems engineering
Semantic XPath query transformation: opportunities and performance
DASFAA'07 Proceedings of the 12th international conference on Database systems for advanced applications
A utilization of schema constraints to transform predicates in XPath query
DEXA'10 Proceedings of the 21st international conference on Database and expert systems applications: Part I
A prototype of a schema-based XPath satisfiability tester
DEXA'06 Proceedings of the 17th international conference on Database and Expert Systems Applications
ADBIS'06 Proceedings of the 10th East European conference on Advances in Databases and Information Systems
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XPath queries are essentially composed of a succession of axes defining the navigation from a current context node. Among the XPath query axes family, child, descendant, parent can be optionally specified using the path notations {/,//,..} which have been commonly used. Axes such as following-sibling and preceding-sibling have unique functionalities which provide different required information that cannot be achieved by others. However, XPath query optimization using schema constraints does not yet consider these axes family. The performance of queries denoting the same result by means of different axes may significantly differ. The difference in performance can be affected by some axes, but this can be avoided. In this paper, we propose a semantic transformation typology and algorithms that transform XPath queries using axes, with no optional path operators, into semantic equivalent XPath queries in the presence of an XML schema. The goal of the transformation is to replace whenever possible the axes that unnecessarily impact upon performance. We show how, by using our semantic transformation, the accessing of the database using such queries can be avoided in order to boost performance. We implement the proposed algorithms and empirically evaluate their efficiency and effectiveness as semantic query optimization devices.