Firebase Firestore。 "Cost"onSnapshot

Question

我需要在页面上放置一个大约 20 个 Vue 组件。每个组件在挂载时都会为自己创建一个 onSnapshot，相应地，当它被删除时会创建一个 unsubscribe()。

const ref = firebase.firestore().collection('components').doc('comp1')

var unsubscribe = ref.onSnapshot(querySnapshot => {
  querySnapshot.forEach(doc => {
     ...
  })
}

每次onSnapshot/unsubscribe 的成本是多少:

1. 在执行时间的意义上
2. 在金钱意义上(根据 Firebase 的价格)

例如，如果 1000 个用户每人在半小时内更新一个包含 20 个组件的页面 100 次，我将支付多少费用？

也许在整个 collection 组件上制作 onSnapshot 会更好？

Answer 1

在Firestore documentation中找到您需要的信息

Listening to query results

Cloud Firestore allows you to listen to the results of a query and get realtime updates when the query results change.

When you listen to the results of a query, you are charged for a read each time a document in the result set is added or updated. You are also charged for a read when a document is removed from the result set because the document has changed. (In contrast, when a document is deleted, you are not charged for a read.)

Also, if the listener is disconnected for more than 30 minutes (for example, if the user goes offline), you will be charged for reads as if you had issued a brand-new query

因此，每次更新集合中的记录时，所有订阅的用户都会执行一次读取。您应该花时间估算您将拥有的活跃用户数量以及数据的数量/频率，这将有助于采用适合您的应用的最便宜和最好的解决方案。

我还添加了默认的 Firebase pricing calculator它位于页面底部，一定会帮助您做出决定。