It can and is done.  Place I last worked at built an in house data model and lookup engine on MS SQL Server to find relations between arbitrary data points on edges.  I know that it is currently used live in production and handles real time fraud evaluation at a large scale (it&#x27;s a private company and not a liberty to disclose actual payment volume).  With proper indexing and careful design it is scalable, but as with everything, you need to dedicate time to performance analysis and design work.