Is there any way to atomically update two collections in MongoDB?

Question

I have a collection of messages:

{
    messageid: ObjectId
    userid: ObjectId
    message: string
    isread: true|false
}

and a collecti

Answer 1

No, unfortunately this isn't possible. MongoDB only supports atomic operations within the scope of a single document. There's no way to perform a transactional operation across multiple documents, even if they're in the same collection.