Chinese walls.
This was something IBM are working on (I had a visit to Hursley a while back) that was of interest for organisations that have distinct datasets they want to share, but haven't got the regulatory or GDPR agreements for. In our case it was insurers and trying to match policy and marketing details.
If you hold them in a Homomorphic database, then you can query them without breaching data protection or regulatory issues. The queries have to be predefined. You can't run an ad-hoc "SELECT * FROM Customers", but you can run "SELECT SUM (premiums) FROM Customers WHERE CustomerID IN (SELECT ProspectID FROM MarketingDB.Prospects)
Biting the hand that feeds IT
