Forum Model For MongoDB

First off, I hope you have read the docs on Schema Design, which explains with an example similar to yours.

So, you can embed or link according to your choice. I would embed if the number of comments are expected to be manageable (relatively smaller) and link if there would be too many comments.

Embedding has the advantage that only one single DB call is required to show a single post/thread and most usually can send just the mongodb response to the browser as is (if client side does the UI rendering). *Note: And adding a comment will require an UPDATE using $push. And do remember that the comment._id has to be created by you, MongoDB won't auto-create it for you. Any updates of comment data in embedded scenario will require an UPDATE with the $ positional operator.*