Storing and Querying XML Documents Using a Path Table in Relational Databases

Abstract

Additional processing is required to store XML documents and to query against them in relational databases due to the discrepancy between the hierarchical structure of XML and the flat structure of relational databases. This paper aims to cope with the issues in storing and querying XML documents with DTD in relational databases. We propose association inlining that extends shared inlining and hybrid inlining to reduce relational fragments and excessive joins. Path expressions of XML documents are stored in the Path table. XML queries written in XQuery are translated into SQL statements by exploiting the schema information that is extracted from the Path table. We also propose a simple method that publishes desired XML data stored in relational databases in XML documents. The structural information is extracted from XML queries written in XQuery and is stored using appropriate structures. Together with the resulting tuples produced by corresponding SQL queries, it is used in publishing relational data in XML documents.