I’m listening to a collection on mongoDB using change streams. I update a document in the collection using the $set query. However, all the arguments in the query don’t actually update the document (some of them just try to set the same value as in the existing document). Now, when I receive the change event for this change in my change stream service, will I see all the arguments I have passed in the query in the updated fields, or will I only see the fields that have actually been modified as a result of executing the query?
Since you already
you propably can answer your own question by printing on the listening side.
But what I can say, is that change streams uses the replication oplog. Hopefully, it is optimized NOT to send unchanged data for replication purpose. My guess is that you do not get unchanged fields. You may ask for the whole document if you absolutly need the unchanged fields.