RWTH Aachen University
XML (eXtensible Markup Language) query processors suffer from main-memory limitations that prevent them from processing large XML documents. While content-based predicates can be used to project down parts of the documents, it may still be needed to resize the obtained projections according to structural constraints. In this paper, the authors consider size, tree-width and tree-depth constraints to enable a structure driven fragmentation of XML documents. Although a set of heuristics performing this kind of fragmentation can be easily devised, a key problem is determining the values of structural constraints input to the above heuristics, given that the search space is prohibitive at large.