Understand Cloud Firestore billing

Question

I have a question because I don't want a $30k bill.

Is this an acceptable code to work with, or is there a better way?

I am using firebase 8.10.0 with Vue.js 2.6.11 and I created the index in firestore.

If there are 1000 documents in the collection "users" and I need to apply filters in the query before making the request for only 50 using this code:

let users = db.collection("users");

users
.where("country" "==" "uk")
.where("online" "==" true)
.where("status" "==" "play")
.orderBy("time", "asc")
.startAt(startTime)
.endAt(endTime)
.limit(50)
.get().then(() => { .... });

Will I be charged for 50 readings or 1000 readings or how much?

What do they mean by "Cursors" in Understand Cloud Firestore billing?

Answer 1

You are charged for the number of documents that need to be read from the server. Since you only read at most 50 documents, you will never be charged for more than 50 document reads with this query. No matter if the collection has 50 documents, or 50 million documents, the charge for this query will be no more than 50 document reads.

The only exception to this general rule is if the query has no results. In that case you will be charged one document read.