firebase - Firestore: request for a list of collection IDs

Question

Firestore documentation says:

Queries other than document reads

For queries other than document reads, such as a request for a list of collection IDs, you are billed for one document read. If fetching the complete set of results requires more than one request (for example, if you are using pagination), you are billed once per request.

I can not find any information of how to perform such queries - to get only IDs.

Anyone knows how?

Answer 1

Waitting for answers