@Joseph_Gan When I say make the update at the application level, I mean that whenever the application makes an update to the profile_name, the application would need to make updates to all of the collections where profile_name is set. It would look like the code block you created.
Yes, you’re totally right about the cons. The application developers would need to be aware of all of the places profile_name is set and make all of the updates in every piece of the application where the update is made.
updateMany() is a wrapper on top of bulkWrite(), so the performance is the same.
I’m trying to think through the example you gave regarding concurrency. I can’t think of why you would want to set the profile_name in collection-f explicitly. You would probably want to only make the update in the epd collection and then push the changes out everywhere else.