On the Updatability of XML Views Published over Relational Data

Updates over virtual XML views that wrap the relational data have not been well supported by current XML data management systems. This paper studies the problem of the existence of a correct relational update translation for a given view update. First, we propose a clean extended-source theory to decide whether a translation mapping is correct. Then to answer the question of the existence of a correct mapping, we classify a view update as either un-translatable, conditionally or unconditionally translatable under a given update translation policy. We design a graph-based algorithm to classify a given update into one of the three update categories based on schema knowledge extracted from the XML view and the relational base. This now represents a practical approach that could be applied by any existing view update system in industry and in academic for analyzing the translatability of a given update statement before translation of it is attempted.