Free MongoDB C100DEV Exam Questions

Question 1

In your database there is a collection named trips with the following document structure:

{

'_id': ObjectId("572bb8222b288919b68abf6d"),

'trip_duration': 858,

'start_station id': 532,

'end_station_id': 401,

'bike_id': 17057,

'start_station_loc': { type: 'Point', coordinates: [ -73.960876, 40.710451 ] },

'end_station_loc': { type: 'Point', coordinates: [ -73.98997825, 40.72019576 ] },

'start_time': ISODate("2016-01-01T00:09:31.000Z"),

'stop_time': ISODate("2016-01-01T00:23:49.000Z")

}

How can you extract all trips from this collection ended at stations that are to the west of the -73.5 longitude coordinate?

A : db.trips.find( { 'end_station_loc.coordinates.0': { $gt: -73.5 } } )

B : db.trips.find( { 'coordinates': { $lt: -73.5 } } )

C : db.trips.find( { 'end_station_loc.coordinates.0': { $lt: -73.5 } } )

D : db.trips.find( { 'end_station_loc.coordinates.1': { $lt: -73.5 } } )

Answer: C

Question 2

You are tasked with developing a high-performance application using MongoDB as your primary database. The application heavily relies on queries that retrieve user profiles based on user names and their location. Given this requirement, you decide to implement a strategy to make these queries more efficient. What strategy should you implement to ensure these queries are covered queries?

A : Use the $project operator in the aggregation pipeline to include only the username and location fields in the result set.

B : Create separate indexes on the username and location fields and include only these fields in the queries.

C : Use the $match operator in the aggregation pipeline to filter documents based on username and location.

D : Create a compound index on the username and location fields and project only these two fields in the queries.

Answer: D

Question 3

You are developing a MongoDB application where write performance is a critical requirement. Given a scenario where your application primarily performs insert operations and rarely performs updates or deletes, which of the following MongoDB features would best optimize this heavy-write workload?

A : Change Streams

B : Capped Collections

C : Aggregation Pipeline

D : Sharding

Answer: D

Question 4

You are designing a MongoDB schema for an e-commerce platform. The platform has three main collections: Products, Orders, and Users.Products Collection: Contains information about each product, such as its name, price, and description.Orders Collection: Contains details about each order, including the userId (referencing the Users collection), an array of productIds (referencing the Products collection), and the total order amount.Users Collection: Contains user details, such as name, email, and address.Which of the following data modeling approaches represents an anti-pattern in MongoDB?

A : Referencing Orders within the Users collection by storing an array of orderIds.

B : Creating a separate ProductDetails collection and storing all product details there, referencing it from the Products collection.

C : Referencing productIds in the Orders collection instead of embedding full product details.

D : Embedding user details directly in the Orders collection.

Answer: B

Question 5

You are working on a MongoDB database for a library system. The system tracks book information in a Books collection. A typical document in this collection looks like this:

Original Document:

{

"_id": ObjectId("book_id"),

"title": "The Art of Computer Programming",

"author": "Donald Knuth",

"genres": ["Computer Science", "Algorithms"],

"published_year": 1968,

"copies_available": 3

}

You are asked to update the document by replacing it with the following document:

Updated Document:

{

"title": "The Art of Computer Programming",

"published_year": 1973

}

After this update, what will the final document in the database look like?

A : { "_id": ObjectId("book_id"), "title": "The Art of Computer Programming", "published_year": 1973}

B : { "_id": ObjectId("book_id"), "title": "The Art of Computer Programming", "author": "Donald Knuth", "genres": ["Computer Science", "Algorithms"], "published_year": 1973, "copies_available": 3}

C : { "title": "The Art of Computer Programming", "published_year": 1973, "author": "Donald Knuth"}

D : { "_id": ObjectId("book_id"), "title": "The Art of Computer Programming", "published_year": 1973, "genres": ["Computer Science"]}

Answer: A