Question 1

In MongoDB schema design, what is a critical implication to consider when adding another piece of data into an array field, especially in the context of document size limitations and performance?

Options :

A : Arrays do not impact document size, allowing for unlimited data addition without performance concerns.

B : Adding elements to an array increases the risk of exceeding the BSON document size limit, potentially leading to failed updates.

C : Adding data to arrays significantly improves query performance by utilizing array-specific indexes.

D : Each addition to an array requires a complete document rewrite, which has no impact on performance or storage.

Answer: B

Question 2

In an e-commerce application, the main entity Product includes details such as name, description, and price. Each Product can have multiple Review documents, which include ratings and customer comments. The application frequently displays products along with their reviews. How should the developer optimize the schema for read performance?

Options :

A : Embed Review documents within the Product document as an array of subdocuments.

B : Store each Review in a separate collection and use the Product ID to link to each Review.

C : Create a separate Review collection and a ProductReview join collection to manage the many-to-many relationship.

D : Store Review documents in a separate collection without storing a reference to the Product ID.

Answer: A

Question 3

When modeling a content management system in MongoDB, which approach best describes the handling of articles and their corresponding comments to optimize for frequent reads and occasional writes?

Options :

A : Articles and comments should be stored in separate collections, with comments embedding the full article document for efficiency.

B : Each comment should be stored in its own collection with a reference to its parent article ID.

C : Store each article in its own document within a single collection, with comments embedded as an array of subdocuments within each article.

D : A relational database management system must be used, as MongoDB cannot efficiently manage hierarchical data like articles and comments.

Answer: C

Question 4

In a MongoDB database, the events collection stores documents related to various events with fields like eventId, title, location, and date. The schema needs to be updated to support a new tags array field, which will store keywords related to each event. What is the most effective way to introduce this change, ensuring backward compatibility and minimal disruption to the existing application?

Options :

A : Create a separate collection named eventTags to store tags with references to their corresponding events by eventId, and adjust the application to aggregate data from both collections.

B : Introduce a schemaVersion field in the documents of the events collection, setting it to 2 for documents including the tags field, and modify the application to handle documents based on their schema version.

C : Add the tags field with an empty array as the default value to all existing documents in the events collection, requiring minimal application changes.

D : Migrate all documents to a new collection named events_v2, including the tags field for new documents, and update the application code to reference the new collection.

Answer: B

Question 5

A MongoDB data modeler needs to optimize a collection named orders to efficiently query documents based on the status field, which can have values like 'pending', 'completed', and 'canceled'. The collection has millions of documents, and the queries should return results quickly even under heavy load. Which of the following approaches best achieves this requirement while maintaining the collection's scalability and performance?

Options :

A : Create a separate collection for each status value and distribute the documents accordingly, querying the relevant collection based on the status.

B : Index the status field using a single field index, ensuring queries filtering by 'status' are more efficient.

C : Convert the status field into an array and use a multi-key index, ensuring multiple status values can be queried simultaneously.

D : Use a hashed index on the status field to evenly distribute the documents across the collection.

Answer: B