A Virtual Health Record (VHR) provides a virtual view of heterogeneous data sources, using a common data model. In contrast to the data warehousing approach in which heterogeneous data is extracted, transformed and stored in a homogeneous form, the VHR approach does not require clinical data to be extracted from existing data stores. Instead, logical queries are defined in terms of a common data model and then transformed into a set of physical queries which can each be executed locally on an individual data store.
illustrates an architecture which supports querying over a VHR.
Querying using a Virtual Health Record
The process of transforming the logical query into separate physical queries may involve translating: