Object Views and Updates

Annotation: Describes how the O2 ODBS supports object-oriented views and data updates made to those views. A view is a virtual schema and base (set of persistent roots), defined using a view definition language (VDL). The view is expressed in terms of the root (underlying) schema and base. The paper defines completeness and consistency constraints on the view, and requires that updates made to the view respect those constraints. An update to a data attribute in a view is translated to updates on root data as follows: if an attribute in the root is the same (or renamed) in the view, then updates to the attribute view are made to the root. If the attribute in the view is defined as a function of the root attribute, and if the function is invertible, then an update is applied to the root by first applying the inverse of that function (e.g., if the view is root x 2, then new-root is new-view / 2). If the function is not invertible, then the user may define code that translates view updates to root updates. A runtime check made after such updates ensures that the new root value still maps to the new view value (if this check fails, the update aborts). Finally, if no translation is possible, the update fails.

BibTeX entry:

@inproceedings{amer-yahia96object,
   author = {S. Amer-Yahia and P. Breche and C. Souza},
   title = {Object Views and Updates},
   booktitle = {Proc. of
	Journ{\~A}\leavevmode\hbox{\raise.6em\hbox{\copyright}}es Bases de
	Donn{\~A}\leavevmode\hbox{\raise.6em\hbox{\copyright}}es
	Avanc{\~A}\leavevmode\hbox{\raise.6em\hbox{\copyright}}es},
   year = {1996},
   url = {http://citeseer.ist.psu.edu/amer-yahia96object.html}
}