Stage 1 · Lesson 2 of 8

When MongoDB fits, and when it does not

MongoDB fits data that is read and written as whole units: a product with its variable attributes, a user profile, an event log, content with nested sections. It also scales out across machines when a single server is not enough. It is a poor fit for highly relational data that you query from many directions, such as a school system where students, courses, teachers and rooms all link to each other, and for work built around transactions across many entities, such as double-entry accounting.

MongoDB supports joins and , but relying on them everywhere means you are paying for a while working against it. A is often the sensible default.

Common trapchoosing MongoDB because feels familiar, then rebuilding joins and constraints by hand in application code.

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Resources for this stage

Start with

CourseFree
MongoDB University
MongoDB
Free: start with the introduction to MongoDB and Atlas setup lessons, which use the same sample data

Practise

Mongo Playground
Paste a few documents and a query and run it in the browser, no install needed

Keep handy

MongoDB Shell (mongosh)
The mongosh docs: connecting, running scripts and the shell helpers such as show and use
MongoDB Compass
The Compass docs for the Schema, Explain Plan and Aggregations tabs you will use later

Also worth your time

PostgreSQL vs. MongoDB vs. DynamoDB (opens in a new tab)Read
A balanced comparison of where a document database fits and where a relational one wins