Universit"at Mannheim

Abstract We introduce Natix, an efficient, native repository for storing, retrieving and managing treestructured large objects, preferably XML documents. In contrast to traditional large object (LOB) managers, we do not split at arbitrary byte positions but take the semantics of the underlying tree structure of XML documents into account. Our parameterizable split algorithm dynamically maintains physical records of size smaller than a page which contain sets of connected tree nodes. This not only improves efficiency by clustering subtrees but also facilitates their compact representation. Existing approaches to store XML documents either use flat files or map every single tree node onto a separate physical record. The increased flexibility of our approach results in higher efficiency. Performance measurements validate this claim. 1 Introduction The concept of semistrucured data has gained wide acceptance, especially in the incarnation of XML (extensible markup language, [1]). XML is being adopted as an easy-to-write, easy-to-parse language to exchange semistructured data in commercial, financial, medical, scientific and other applications