Mongoose is a client-side library. It emulates relations and schemas client-side, as I also pointed out in the article.This also means that the database cannot optimize for relations and schemas, as it doesn't even know they exist.
Mongoose is also very much not the default MongoDB client in Node.js - it's a third-party client library by Automattic. The official client according to the MongoDB documentation is `mongodb` (https://www.npmjs.com/package/mongodb), which does not feature relations.
I actually didn't even notice Mongoose being mentioned on that page, to be honest, given that the instructions were for `mongodb`. I'd imagine that neither would a developer skimming the page :)
Mongoose is also very much not the default MongoDB client in Node.js - it's a third-party client library by Automattic. The official client according to the MongoDB documentation is `mongodb` (https://www.npmjs.com/package/mongodb), which does not feature relations.