The norm is when relationships are used in Mongo? For example, a Collection of "group" contains an array ref "people" -- the people who are in this group. How to be better to build people whole object or the link? And another point, if some "people" just have to refer collection of the "establishment", then there is also the link or embed and there, and here as a whole person? But if you embed a whole, then the difficulty in synchronizing the age of the data person, all of a sudden the original person will change their fields, will have to propagates to all the places where this person is, and update its fields.