Extending XML document projection for data integration

We are developing a mediated data integration system based on XML, XML schema, and XQuery. One of the challenges for mediators is how to retrieve only relevant data from data sources to answer queries. We extend Amelie Marian and Jerome Simeon's XML document projection algorithm to pinpoint the relevant data. Thought their original algorithm is very effective for reducing main memory consumption of XQuery processors, it does not analyze navigations in constructed elements and thus is not effective for our mediation system. We present inference rules for navigation analysis on constructed elements with literal names in this paper. This extension improves not only our system but also main memory XQuery processors.