Does a heavy document take much time in load from Firestore?

Question

I am using both Firebase Database and Firestore in my app. I store users data like name, email, uid etc small details in documents of a collection as Users in firestore. It works perfectly. I made a node as Friends in firebase database to store friends list of a user. So whenever user open the app, it calls his information from Users from firestore and also his friends list from Friends from firebase database.

Now the thing is by this way it calls data from the Firestore and the Firebase database. So it means they are 2 requests/reads, one to Friends node and other to a document from Users collection. I think it would be better if i store friends list in Users document as an Array. So i will get only 1 read in Firestore. But i think that when the arrays of his friends list increases by 100+ elements. And also there are one or two more array lists like that. So will it take much time in retrieving a document from Users collection? or not? And which will be a better approach?

Here are the images of my current database structure as Users and Friends.

Answer 1

As per the Firestore usage and limits, the maximum size of a document is 1 MiB.

It means that as long as your user documents don't exceed the size limit, you can store friends data in arrays without a problem.

If you are planning to exceed the threshold, you may want to look for other options like creating subcollections to scale better as size of the subcollection doesn't affect the parent document's size in any way.