Question 1

A mobile application tracks user activities, interactions, and engagement metrics to offer personalized content and recommendations. To optimize the application's performance, particularly for generating monthly engagement reports and user insights, a data modeler is tasked with designing an efficient data storage strategy. What approach should the data modeler adopt to best meet these requirements?

Options :

A : Maintain separate collections for users, activities, and interactions, calculating engagement metrics and insights in real time upon each query.

B : Use a single collection for activities and employ on-the-fly aggregation queries for generating user engagement reports and insights whenever needed.

C : Store all user data, including activities and interactions, as embedded documents within a single user document in a single collection.

D : Utilize separate collections for Users, Activities, and EngagementMetrics. Use the computed pattern to periodically update EngagementMetrics with aggregated data.

Answer: D

Question 2

In a MongoDB database for an online bookstore, you're designing a data model to handle books, authors, and reviews efficiently, considering a complex scenario involving relationships and potential data skew due to varying numbers of reviews per book. Given the requirements:

Each book can have multiple authors.

Each author can write multiple books.

Books can have a large number of reviews, but most have a few or none, creating potential data skew.

The application frequently queries books with their authors and a sample of reviews to avoid performance issues due to data skew.

How should you model the relationships among books, authors, and reviews to optimize for query performance and data management?

Options :

A : Embed authors and a fixed number of top reviews in each book document.

B : Use a separate collection for reviews and link them to books with a book ID. Authors and books are embedded within each other-s documents.

C : Reference authors and reviews in the book document with foreign keys.

D : Embed books within author documents, including all reviews for each book.

Answer: A

Question 3

Regarding MongoDB schema design and document structure, which two of the following statements are accurate?

Options :

A : All documents within a collection must have the same fields and data types.

B : Embedding documents is recommended for frequently accessed data that is read together.

C : Schema validation rules are enforced by default on all collections upon creation.

D : Denormalization can reduce the need for expensive joins and improve read performance.

Answer: B,D

Question 4

When optimizing a MongoDB collection's schema for a high-traffic application, what factor is crucial for determining the most effective document structure?

Options :

A : Modeling documents to reflect the application-s access patterns, prioritizing query performance and data retrieval efficiency.

B : Designing documents based on the visual appeal of the JSON structure in the database management interface.

C : Ensuring all documents in a collection have a uniform size by adding placeholder data where necessary.

D : Organizing fields in alphabetical order within documents to facilitate easier indexing.

Answer: A

Question 5

A developer is building a project management tool where each Project can have multiple Task entities. The tasks are frequently updated and accessed together with their parent project. What is the most efficient way to model this data relationship in MongoDB to optimize for task read and write operations?

Options :

A : Embed Task documents as an array of subdocuments within each Project.

B : Create a separate collection for tasks and projects, linking them through a shared projectId and taskId in a third collection.

C : Store each Task in a separate collection, with a projectId to reference back to their Project.

Answer: A

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