Supporting branched versions on XML documents

Many e-commerce and e-government applications are collaborative in nature (e.g. negotiation and e-catalog management). In collaborative environments, users typically define new document versions from any past version, which creates the need for supporting multiversion XML documents, particularly branched versioning. In this paper, we address the problem of evaluating path expression queries over XML documents with branched versions. We extend path joins to work in a branched version environment and to allow queries on multiple versions. We propose a storage scheme that efficiently maintains all branched document versions and describe changes required on Pathstack, an optimal pattern matching algorithm. Finally, we investigate the effectiveness of our techniques through experimental evaluation.