Firebase JS SDK on 'child_added' not working on large database

Question

I have ~ 1 million users in my users "table" on Firebase.

I need to fetch the username of each user.

once('value' is a way too big of a call, so I try using on 'child_added' but without any success, I am using this code:

usersRef.on('child_added', function (snapshot) {
  var user = snapshot.val();
  console.log(user);
  var username = user.username ? user.username : null;
  // Put username in the .txt file, one username per line
});

I waited as much as 15 minute, and nothing happened. It seems to be impossible right now. What could I try besides child_added?

Answer 1

Retrieving one million nodes is very unlikely to ever work. You're simply trying to pull too much data over the network. In that respect there is no difference between value and child_added: both retrieve the same data over the network in the same way.

Limit the number of children you retrieve by a query, either by a query:

var ref = firebase.database().ref("users");
ref.orderByChild("username").equalTo("Dan P.").on("child_added", ...

or by directly accessing the user's node:

var ref = firebase.database().ref("users");
var user = firebase.auth().currentUser;
ref.child(user.uid).on("child_added", ...