下面的代码失败，错误为9 FAILED_PRECONDITION: The requested snapshot version is too old.

const ref = db.collection('Collection');
const snapshot = await ref.get();
snapshot.forEach((doc,index) => {
   ...use data
})

Getting all documents from one collection in Firestore
编辑：

getData();

async function getData(doc) {

  let snapshot = await global.db.collection('Collection').orderBy().startAfter(doc).limit(5000).get();

  const last = snapshot.docs[snapshot.docs.length - 1];
  
  snapshot.forEach((doc,index) => {
      //...use data
  })

  if (snapshot.docs.length < 5000) {
    return;
  }
  else {
    getData(last)
  }
}

编辑2（工作，有点慢，按顺序读取，一次5000个文档）：

let snapshot = null;
let totalIndex = 0;

await getData();

async function getData(doc) {

  if (!doc) {
    const first = await global.db.collection("collection").doc("docID");
    snapshot = await global.db.collection('collection').orderBy(admin.firestore.FieldPath.documentId()).startAt(first).limit(5000).get();
  }
  else {
    snapshot = await global.db.collection('Prompts').orderBy(admin.firestore.FieldPath.documentId()).startAfter(doc).limit(5000).get();
  }

  const last = snapshot.docs[snapshot.docs.length - 1];
  
  snapshot.forEach((doc,index) => {
     console.log(totalIndex++);
     //...use data
  })

  if (snapshot.docs.length < 5000) {
    return;
  }
  else {
    getData(last)
  }
}