Optimizing DOM programs on XML views over existing relational databases

Since XML has become the de-facto standard for data interchange through the Internet, more and more application programs to process XML data are being developed. On the other hand, a huge amount of existing data is stored in relational databases. We developed a system that allows XML application programs using DOM APIs to take as input relational data through their XML views. A key issue is optimization. We developed an optimization technique having a training mechanism for efficient execution of the programs. This paper presents the system's architecture, the optimization technique, and preliminary experimental results showing that the proposed technique can achieve dramatic performance improvements.