Exam Professional Cloud Developer topic 1 question 108 discussion

Selected: A Firestore has a “hierarchical structure”: collection contains documents, document can contain (sub)collections D does not make sense bc why do you want to link comments to the user profile instead of the article? https://stackoverflow.com/questions/48634227/limitation-to-number-of-documents-under-one-collection-in-firebase-firestore “There is no documented limit to the number of documents that can be stored in a Cloud Firestore collection. The system is designed to scale to huge data sets.”

Why D and not C? For my understanding, we need to keep a relation between the articles and their comments. I don't see how the user profile could come in handy... but please let me know if I misunderstood something. For me, Ans C makes more sense.

Answer A. Comments in article subcollection: Standard Firestore pattern Scales infinitely Easy to query per article Clean data organization No size limits concerns

The best answer here is A. Store each comment in a subcollection of the article. Here's why: Scalability: Storing comments as subcollections within the article document allows you to handle an unlimited number of comments per article. Firestore scales well with large numbers of subcollections. Querying: You can easily query for comments related to a specific article using the collectionGroup() query. This allows you to retrieve all comments for an article without needing to know the specific comment IDs. Performance: Firestore's subcollection structure optimizes for reading and writing comments related to a specific article.

Firestore has a hierarchical structure

It can't be D because: Storing each comment in a document and adding the comment's key to an array property on the user profile wouldn't efficiently link comments to articles.

Answer is D in my opinion for "display user-submitted comments" and "unknown number of comments and articles"

Answer is A

As per previous comments also appointed, there is not such a limitation on size for a Subcollection, and it does not make sense to store the relation with User profile like answer D

Option A is the recommended approach for structuring data in Firestore to support an unknown number of comments and articles. Firestore is a NoSQL document-oriented database, and using subcollections provides a flexible and scalable way to organize related data

I would go with C.

the correct answer is A. reference: https://firebase.google.com/docs/firestore/data-model

Answer is D

Firestore has a "hierarchical structure"

It is recommended to add the comment document IDs to an array property on the corresponding article document, rather than on a user profile. This approach allows you to easily retrieve all comments for a specific article by querying the comments collection using the article ID and then filtering the results based on the IDs in the article's comments array. Storing the comment IDs in the article document also avoids the need to make multiple read operations to retrieve the comments for a given article, which can be slow and increase latency. For example, you could create an array property named "comments" in the article document and add the comment document IDs to this array every time a user submits a new comment for the article. This allows you to efficiently retrieve all comments for a given article by querying the comments collection and filtering based on the IDs in the article's "comments" array.

Close to this example: https://firebase.google.com/docs/firestore/data-model#subcollections

Answer is A. Store each comment in a subcollection of the article, because it allows for easy scaling and querying of the comments as the data increases. With this approach, you can easily fetch the comments associated with an article by querying the subcollection of that article, instead of querying all the comments in a single collection. It also allows you to query specific comments and articles easily, since you have the reference to the specific article they are associated with.