Staying with data modeling, but moving to the world of document databases, Ayende has two great posts about modeling an auction system: part 1 and part 2. They are great not only because it’s not the Human-has-Bird-and-Cat-and-Dogs example, but also because he looks at different sets of requirements and offers different solutions.
That is one model for an Auction site, but another one would be a much stronger scenario, where you can’t just accept any Bid. It might be a system where you are charged per bid, so accepting a known invalid bid is not allowed (if you were outbid in the meantime). How would we build such a system? We can still use the previous design, and just defer the actual billing for a later stage, but let us assume that this is a strong constraint on the system.
Original title and link: Data Modeling for Document Databases: An Auction and Bids System ( ©myNoSQL)