How do I do this?

Is there a way to define a attribute in the Identity vault and not store the value, and when the vaule is requested the engine performs a backend query?

For example: A salary attribute is defined in a HR driver but is not synced to IDV but when another driver asks for the IDV salary attribute value the engine queries the HR driver and pass it on..

I recall I saw something similar at Brainshare a few years ago..

T.I.A
//magnus