Meteor CRUD many-to-many relationships MongoDB

Question

I have 3 collections interconnected through many-to-many relationships. Therefore, I have 2 concerns:

1. Should I have 2 arrays with 2 ids in each of the 3 collections, or one join collection with 3 ids?
2. How to perform reads, inserts, updates and deletes, so everything is in sync and integrity is ensured?

Answer 1

For most scenarios, I'd probably have the referencing IDs on each of the objects, like this:

{
  "_id": "123",
  "firstReferenceCollectionId": "abc",
  "secondReferenceCollectionId": "def"
}

If your application is going to have massive scale, I'd probably further denormalize the data based on how it's actually being used.

To answer your second question, you really shouldn't need to worry about that with the above approach, since the internal id of the reference won't change when other properties on those objects change. If you go the route of additional denormalization, use meteor add matb33:collection-hooks to sync up data on upserts. Here's the documentation link: https://github.com/matb33/meteor-collection-hooks