I was just reading about pricing in Firebase and came across the terms Ingress and Egress traffic. According to Firebase's pricing documentation, Ingress is free. I wanted to make sure that I understand these terms correctly, so here is my interpretation:

• Ingress: Data traffic that comes from the "outside" (a user) to my Firebase service.
• Egress: Data traffic that is sent from my Firebase service to the "outside".

CodePudding user response：

Ingress is free.

No, it's not. When you add data to Firestore, you have to pay a write operation for each document you add/update. On the other hand, when you read data, you have to pay a read operation for each document a query returns. Even if your query yields no result, according to the official documentation regarding Firestore pricing, it said:

Minimum charge for queries

There is a minimum charge of one document read for each query that you perform, even if the query returns no results.

Edit:

When it comes to reading data from Firestore, besides the writes/reads/deletes we perform, we also need to pay for what we consume, including storage overhead. What does that mean? It means that we have to pay for the metadata, automatic indexes, and composite indexes.

On the other hand, when you perform a write, you don't have to pay for bandwidth, since a write operation is not followed by a read operation unless you perform that explicitly.