Since some of the difficulty lies with the relational model itself, it will be very interesting to see how they deal with the problem. Implementing query tools for a dimensional structure is simultaneously much simpler and much more difficult than for a 'traditional' normalized model. Optimization, indexing and so on, become much simpler problems. See the last section below. Query tools are more difficult since they must be able to provide a clear differentiation between questions that have subtle differences in statement.
Hospital buying groups sign contracts with manufacturers in order to receive better pricing.
However, individual hospitals may not participate in some contracts. That is, a member of a buying group may purchase the products covered under a contract with one buying group via a different contract with a different buying group. Hence, the question as to what a hospital buys when they are a member is different from the question about what they buy under the group contract. This is a subtle yet enormous difference. I have always thought that a query tool that presented the ER diagram would be wonderful from the enduser's perspective.