Queries scale with the size of your result set, not the size of your data set

Question

This is a question about the latest Firebase Cloud Firestore.In this doc it says like this:

It also allows for expressive queries. Queries scale with

Answer 1

This may be written a bit confusing. It is not a use-case in the classic sense its just a statement about the performance of Firestore.

It basically says that it does not matter if you request 1 item out of a 100 or 1 item out of 100.000.000, it will be equally fast. Here 1 is your result set and 100/100.000.000 is your data set. So requesting 1 item out of 100.000.000 will be faster than requesting 50 items out of 100.

I hope this makes it a bit clearer!