E-Commerce Site Data Model

Hello, I was reading Desiging Data-Intensive Applications and was thinking what is the best way to design an E-Commerce site's (such as Amazon) data model? My idea would be to create a hybrid of a RDS and Document Model. I'd use an RDS to storemy user information and order information. Then use a document database to store product information because each product might have very different characteristics, and a set schema doesn't make sense. I could go into more detail, but really I am just curious how to most e-commerce websites set up their data model, especially when selling a wide range of products and or services that might not fit into a structured data model?