Join Operation over XML Data

H-C. Liu (Taiwan) and G. Dobbie (New Zealand)


XML, objectrelational databases, query processing


We propose a novel approach of mapping XML documents to the object-relational form and then to cor responding nested tables, and explore the join problem on the XML data by applying a path join operator to the mapped nested tables. It is demonstrated in this paper that object-relational database systems need to augment their suite of physical join algorithms to include nested table join to be competitive on XML query process ing. Our P-join operator turns out to be superior to traditional traverse-style algorithms. The results of this paper can be used as a basis to develop and configure more sophisticated object-relational mapping schema and perform algebraic optimization after transforming queries expressed in XML-QL into SQL3.

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