Cost for sub collection read in a document Firestore

Question

I have structured my data in firestore as: Collection Reference: "Post" And each Post has Array of String as Images, Array of String as usersLiked, Caption.

So when I am try to read a Post, and that Particular Post has 3 image strings, and 3 userId's under usersLiked, how many reads do I get for:

images.length
usersLiked.length
checking usersLiked contains the userId of currentUser

Does each string in the sub collections count as one document read?

Thank you all for your help: I am a beginner and I would appreciate any help with advise on structuring my database efficiently in terms of cost and efficiency.

user_13109852 · Answer

Every document you access its content is readable. The sub-collection doesn't matter.

"Each returned document from your query counts as 1 read."

I also recommend checking out here: 1- https://firebase.google.com/docs/firestore/pricing 2- https://firebase.google.com/docs/firestore/billing-example

Cost for sub collection read in a document Firestore

1 Answers