If relations are embedded in a document then you favour querying from the "side" of the relation that is the outer document. But usually you cannot anticipate f

If relations are embedded in a document then you favour querying from the "side" of the relation that is the outer document. But usually you cannot anticipate from what sides of the relation you may want to query in the future. As such, MongoDB may scale nicely for performance, but it doesn't scale nicely for business needs. A relational database is completely unbiased in that regard, you do not need to make nor encode any decision on what would be the "outer" document or inner nested objects. It's all just entities and relations.