A virtual data view is essentially a physical data view on which certain transformation actions have been defined. The transformation actions take place in real time, to create the virtual data view. The following figure shows how transformation actions are defined on a physical data view to create a virtual data view.
In addition to the transformation actions, certain properties can be defined on a data view, which restrict the way in which data can be managed through that data view. The additional virtual data view properties are described in Additional Virtual Data View Properties.
Virtual data views imply a performance impact. The significance of the performance impact depends on several factors including the size of the physical data source, the complexity of the transformation, and the complexity of any virtual ACIs you might use.