I am using firebase cloud code and firebase realtime data database. My database structure is:

 -users
       -userid32
       -userid4734
          -flag=true  
       -userid722
          -flag=false
       -userid324

I want to query only the users who's field 'flag' is 'true' What i am doing currently is going over all the users and checking one by one. But this is not efficient, because we have a lot of users in the database and it takes more than 10 seconds for the function to run:

const functions = require('firebase-functions');
const admin = require("firebase-admin");
admin.initializeApp(functions.config().firebase);

exports.test1 = functions.https.onRequest((request, response) => {
    // Read Users from database
    //
    admin.database().ref('/users').once('value').then((snapshot) => {
        var values = snapshot.val(),
            current, 
            numOfRelevantUsers,
            res = {};       // Result string
            
        numOfRelevantUsers = 0;
            
        // Traverse through all users to check whether the user is elligible to get discount.
        for (val in values) 
        {
            current = values[val]; // Assign current user to avoid values[val] calls.
            
            // Do something with the user
        }
            
        ...
});

Is there a more efficient way to make this query and get only the relevant records? (and not getting all of them and checking one by one?)

I am using Firebase cloud code and firebase realtime database.

My database structure is:

 -users
       -userid32
       -userid4734
          -flag=true  
       -userid722
          -flag=false
       -userid324

I want to query only the users who's field 'flag' is 'true' .

What I am doing currently is going over all the users and checking one by one. But this is not efficient, because we have a lot of users in the database and it takes more than 10 seconds for the function to run:

const functions = require('firebase-functions');
const admin = require("firebase-admin");
admin.initializeApp(functions.config().firebase);

exports.test1 = functions.https.onRequest((request, response) => {
    // Read Users from database
    //
    admin.database().ref('/users').once('value').then((snapshot) => {
        var values = snapshot.val(),
            current, 
            numOfRelevantUsers,
            res = {};       // Result string
            
            numOfRelevantUsers = 0;
            
        // Traverse through all users to check whether the user is eligible to get discount.
        for (val in values) 
        {
            current = values[val]; // Assign current user to avoid values[val] calls.
            
            // Do something with the user
        }
            
        ...
});

Is there a more efficient way to make this query and get only the relevant records? (and not getting all of them and checking one by one?)