I have a scenario where I need to validate a domain using values in another domain. Rule is : Each value in domain 1 must exist in domain 2. The list of unique values in second domain will be around 50 million. How do I do this in DQS?
That isn't readily possible. It isn't a feature that I know of.
What kind of scenario are you working on - names or something?
1. You can make a linked domain which is essentially a duplicated view atop the first domain with a different name. The values stored in the original domain are the same as the linked domain copy of the domain.