My site on GAE allows people to create postings. It also allows people to edit postings and review them.
Users should be able to retrieve a list of postings they have created, list of postings they have edited and a list of postings they have reviewed. Also, it would be nice to be able to view all reviews for a product.
Two solutions present themselves and I was wondering as to the pros and cons of each:
Solution 1: in user object/entity store lists containing the ids of created or edited or reviewed postings.
Solution 2: Store a mapping. So for every review (for example) store a new entity that contains userId and posting Id. Retrieve all postings created by a specific user using a query.
Which would you advise?
Solution 2 seems more scalable but more costly.