Integrating keyword search into XML query processing

Due to the popularity of the XML data format, several query languages for X ML have been proposed, specially devised to handle data of which the struct ure is unknown, loose, or absent. While these languages are rich enough to allow for querying the content and structure of an XML document, a varying or unknown structure can make formulating queries a very difficult task. We propose an extension to XML,query languages that enables keyword search at the granularity of XML elements, that helps novice users formulate queries , and also yields new optimization opportunities for the query processor. W e present an implementation of this extension on top of a commercial RDBMS; we then discuss implementation choices and performance results. (C) 2000 P ublished by Elsevier Science B.V. All rights reserved.