3. Semantic data model realization example

The drawing below depicts fragment of geophysical, geological and production information database having been realized on the semantic data model basis. This fragment incorporates following objects: oilfield, well, repair and team. Parameters' values of these objects are supplied with relations to other objects and domains (relations' names are shown in rectangles located inside the objects at the left). Stored in the domains values can be both discrete and continuous.

Parameters whose values are data arrays (repairs, for example) rather than single numbers are allocated in the table framework. But the values in the framework cells as well as the rest values in the base are accessed by means of the references. Given example explains that all the values are stored in the base at a single location, namely, at the corresponding domain. Under such an approach a domain becomes a potential object or pseudo-object. Its function is quite understandable provided we take into account the fact that database parameters specification has often to be extended. Let us imagine, for example (see figure 1), that we have decided to add to the database some oilfield attributes. In this case pseudo-objects composing the Oilfield names domain are converted to fully-grown objects described by defined parameters set. Such an approach benefit is that parameters specification extension concerns only those base objects added parameters are directly related to. Structure of the rest of the base as well as its data are not corrected at all in this case.