是否在Firebase中仅下载部分数据库参考？

const firebase = require("firebase/app");
require("firebase/firestore");

const firebaseConfig = {
  // Your Firebase configuration here
};

firebase.initializeApp(firebaseConfig);
const db = firebase.firestore();

const collectionRef = db.collection("myCollection");

// 获取所有年龄大于18的数据
collectionRef.where("age", ">", 18).get().then((querySnapshot) => {
  querySnapshot.forEach((doc) => {
    console.log(`${doc.id} => ${doc.data()}`);
  });
});

const firebase = require("firebase/app");
require("firebase/firestore");

const firebaseConfig = {
  // Your Firebase configuration here
};

firebase.initializeApp(firebaseConfig);
const db = firebase.firestore();

const collectionRef = db.collection("myCollection");
const pageSize = 3;

// 获取前3个数据
collectionRef.orderBy("timestamp").limit(pageSize).get().then((querySnapshot) => {
  querySnapshot.forEach((doc) => {
    console.log(`${doc.id} => ${doc.data()}`);
  });
});

const firebase = require("firebase/app");
require("firebase/firestore");

const firebaseConfig = {
  // Your Firebase configuration here
};

firebase.initializeApp(firebaseConfig);
const db = firebase.firestore();

const collectionRef = db.collection("myCollection");

// 只获取name和age字段
const snapshot = await collectionRef.where("age", ">", 18).select("name", "age").get();

snapshot.forEach((doc) => {
  console.log(`${doc.id} => ${doc.data()}`);
});