Query Mapping Techniques for XML Documents: A Comparative Study

Extensible Markup Language (XML) has grown to be a promising medium for data interchange and representation over the Internet. In the presence of the database technology there is a growing need to develop efficient storage and querying large repositories of XML documents. Numerous researchers proposed various mapping approaches using Relational Database (RDB) to store and query XML documents. These approaches are categorized into two: structure-mapping and model-mapping approaches. Various query mapping techniques (Edge-based, Node-based, and Path-based) are proposed and applied on the existing model mapping approaches. These techniques translate XPath query into Structured Query Language (SQL) statement with less number of join operations and reduce the search space, and improved the XML query processing. Therefore, the aim of this paper is to compare these query mapping techniques in terms of their advantages and limitations. The implication of these query mapping techniques on the existing model mapping approaches are also discussed. The discussion is focus on the complexity of translated SQL and query response time, which affect the efficiency of the XML query processing. Finally, the effectiveness for each technique on XML query processing and the solutions are pointed out.