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MongoDB · Module 4 of 10

Data modelling

Choose between embedding and referencing.

📖 Key ideas

  1. Embed related data read together (e.g. address inside user).
  2. Reference with ids when data is large or shared (e.g. orders → user_id).
  3. Design for your queries: how will the app read data?
  4. Document size limit is 16 MB.
  5. Avoid unbounded arrays that grow forever.
💡 Real-life example: Embedding is keeping the charger in the phone box; referencing is a note saying "charger in drawer 3".
EmbeddingStoring related data inside a document
ReferencingStoring an id pointing to another document
16 MBMax document size
Unbounded arrayArray that grows without limit