Querying Semi-structured Data with Mutual Exclusion

Data analytics applications, content-based collaborative platforms and office applications require the integration and management of current and historical data from heterogeneous sources. XML is a standard data format for information. Thanks to its semi-structured-ness, it is a good candidate data model for the integration and management of heterogeneous content. However, the management of historical and collaboratively created data compels considering extensions of the original XML model to constraint-based, probabilistic and temporal aspects. We consider here an extension of the XML data model with mutual exclusion between nodes for the purpose of the management of versions in XML databases. XML query processing algorithms for ordinary XML data focus on the parent-child, ancestor-descendant, sibling and lowest common ancestor relationships between nodes. In this paper, we extend existing labeling schemes and query processing algorithms for the processing of queries over an extension of the XML data model with mutual exclusion. We focus on structured twig pattern query, and show that the same technique can be applied to keyword queries as well. We empirically evaluate the performance of the proposed techniques.