How to efficiently count the documents in a large Firestore collection.
Obviously, I do not want to get the entire collection and count it on the front end as the money will go through the roof. Is there really not a simple API such as db.collection('someCollection').count() or similar, but we need to hack around it?
CodePudding user response：
Is there really not a simple api such as db.collection('someCollection').count() or similar
No, there is not.
but we need to hack around it
Yes, we can use a workaround for counting the number of documents within a collection, which would be to keep a separate counter that should be updated every time a document is added to, or removed from the collection.
This counter can be added as a field inside a document in Firestore. However, if the documents in the collection are added or deleted very frequently, then this solution might be a little costly, a case in which I highly recommend you to use the Realtime Database. In this case, there is nothing you need to pay when you update the counter, but only when you read (download) it. And since it's just a number, then you'll have to pay almost nothing. I have even written an article a couple of years ago regarding solutions for counting documents in Firestore: