Abstract: Method and apparatus for validating propagation of XML constraints to functional dependencies when transforming XML to relational data. The method includes steps of accepting variables indicative of XML-based data, determining if one of the variables is unique based on checking the validity of XML keys defining XML constraints and determining if one or more fields in said relational data do not have a null value. The variables are selected from a set of XML keys (?), a transformation Rule (R) and a Functional Dependency (?). One determining step includes substeps of viewing a transformation Rule as a Table Tree and traversing nodes in the Table Tree. The nodes are traversed until an XML key is found at a particular node and then said one of said plurality of variables (in one embodiment identified as x) is determined to be unique when compared to the context of said XML key.

Abstract: A set of subscriptions are provided, where one or more subscriptions each comprises a tree pattern, and a tree pattern comprises one or more interconnected nodes having a hierarchy and adapted to specify content and structure of information. The set of subscriptions is used to select information for dissemination to users. Generally, the one or more subscriptions having the tree pattern describe information the users are interested in receiving. Techniques are presented for determining an aggregation from the subscriptions, where the aggregation comprises a set of aggregate patterns. The set of subscriptions may comprise a number of tree patterns, and the aggregate patterns generally also comprise tree patterns comprising one or more interconnected nodes having a hierarchy and adapted to specify content and structure of information. The set of aggregation patterns is smaller than the set of subscriptions and can be made to fit any space constraint.