Firebase realtime db working

Hi , I would like to ask about how the firebase realtime db component works…

*The “firebase datachange” component downloads all the data from the database URL in order to work?
I have more than 1000 tags in the database…
So if the app downloads all that data every time it starts the screen, it would be spending a lot of resources on firebase, right? ,

*Is there any way to prevent firebase from downloading the database? (I’m only interested in sending data but not receiving it), (I have to send the data to that particular bucket so I can’t change the bucket to another one that has 0 tags)

*The data downloaded from the database is saved in the phone memory?