如何减少 Firestore 的文档读取

Question

I am using Firestore (I am new to this) for small web application. Currently, each time when I refresh or go to another page, the function retrieves all the documents in the Firestore. But the data that it retrieves does not change often,

Is there a way for me to retrieve all the data that will cost me little to no document reads?

I am currently using these function to retrieve the data

firebase
.firestore()
.collection("products")
.then((snapshot) => {
       snapshot.forEach((docs) => {
       });
});



firebase
.firestore()
.collection("products")
.where("prodID", "==", prodID)
.then((snapshot) => {
       snapshot.forEach((docs) => {
       });
});

Answer 1

It depends on your app.
But a way to reduce it would be to retrieve them from the cache.
According to the docs ( https://firebase.google.com/docs/reference/android/com/google/firebase/firestore/Source ) you can do something like

function getData() {
   firebase
   .firestore()
   .collection("products")
   .get({source: "cache"})
   .then((snapshot) => {
         if (!snapshot.exist) return getServerData()
         snapshot.forEach((docs) => {
       });
  });
}

function getServerData() {
   firebase
   .firestore()
   .collection("products")
   .get()
   .then((snapshot) => {
         snapshot.forEach((docs) => {
       });
  });
}