Most Recent Document from each CollectionGroup

Question

How do I query the MOST RECENT DOCUMENT from each CollectionGroup in Cloud Firestore?

Just one document from each Collection in the Group, the most RECENT!

Answer 1

Just one document from each Collection in the Group, the most RECENT!

You cannot. When you are using a CollectionGroup query, you are retrieving all documents that exist in all collections that have a specific name. If two of the most recent documents exist within the same collection/subcollection, both will be retrieved. You cannot tell Firestore to get a single document from within each collection, unless you create a separate query for each one of them and use a limit(1) call.