what counts as document reads in firestore?

Question

In Firestore, If my query only returns 10 results that match the critera, but I have to read all the 1000 documents, how much would be counted as document reads in firestore billing?

Answer 1

If my query only returns 10 results that match the critera,

This will only cost 10 reads.

but I have to read all the 1000 documents

If you are saying you have 1000 documents in the collection but your query returns only 10 documents, then that's 10 reads only.