How to share a post in twitter clone app using Firestore as a database?

Question

I have a Firestore data structure and a document where all my followers can see the recentPosts of mine by querying the collection of documents based on the users field of the document where querying users name is present just like below.

my question is how to share a post of others to my followers, currently i am duplicating the shared post to my recentPostsand my seperate Collection of posts documents, but what if a user deletes the post and the post was shared by million users? i have to delete all the shared posts, is there a better solution?

Answer 1

Given your choice in data model, having to delete the duplicated posts is pretty much the normal solution. I also don't see this as problematic, given that:

1. You've already written the duplicate post to all these followers to begin with, so the delete is just another write.
2. Deletes and other writes are relatively uncommon in most applications. If not, consider whether you should really be duplicating the data to all followers.

You could choose to implement this with a global list of deleted posts, that each client then reads. But at that point you're making the code that reads data more complex to prevent writes, which is typically not the best approach when using NoSQL databases.