XML Query Optimization and Wrapping Query Languages for Heterogeneous Information Integration

摘要

In this paper, we address the problem of evaluating XML queries over XML views of heterogeneous information sources. This paper makes two main contributions. The first is a technique that optimizes XML queries by applying a commutative law to XML operators. This technique pushes queries down to the information sources. The second is wrapping the query languages in order to manage the heterogeneity of the information sources. Query capabilities are described as sequences of XML operators. We implement a prototype system and verify that the proposed methods work with relational databases and XPath databases.