Generalizing and Improving SQL/XML Query Evaluation

SQL/XML has gained increasing interest whenever relational data has to be transformed to XML data, which is transferred, stored, or further processed in internet-based systems. However, SQL/XML is not supported by all relational database systems and SQL/XML query processing may become a bottleneck when large amounts of XML data are generated by SQL/XML queries. We have developed a technique to generalize and to improve the evaluation of SQL/XML queries in comparison to the SQL/XML query evaluation techniques provided by the database systems Oracle 11g and DB2. Our generalization supports the SQL/XML transformation of relational data into XML for all relational database systems, including those that up to now support only SQL, but not SQL/XML, and it allows generating compressed or uncompressed XML. The improvement is that our approach does this faster than Oracle 11g and than DB2 in most cases.