title: How can i get the user order without reading all documents in a collection in firebase?
body: <p>I have a collection that includes documents for each user for my app and these documents include the points for each user. I want to get the order of each user. I know that I can get all the documents in the collection, sort them by their points and get the order of the current user. But this approach will require reading every document (if there are 10,000 users, that means 10,000 reads for every time a user wants to see his/her rank) and will increase my bill unnecessarily. I also tried to use cloud functions, but the function using the same logic will also consume read quota as above I guess. Is there a solution that I can get the order of a single user without reading the whole collection?
  Thanks.</p>