Question 1

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?

Options :

A : Change Streams

B : Capped Collections

C : Aggregation Pipeline

D : Sharding

Answer: D

Question 2

Consider a MongoDB database containing a collection of documents representing product information for an e-commerce website. The documents have the following structure:

{

"_id": ObjectId("5f95a1d11a12b400001b75c0"),

"product_name": "Smartphone",

"brand": "Apple",

"price": 800,

"categories": [ "Electronics", "Smartphones" ],

"reviews": [

{ "username": "user1", "rating": 4, "comment": "Great product!" },

{ "username": "user2", "rating": 5, "comment": "Excellent!" },

{ "username": "user3", "rating": 3, "comment": "Good but overpriced." }

]

}

Select the MongoDB aggregation pipeline that returns the average rating of all products grouped by brand. The result should include only brands with an average rating greater than or equal to 4. The output should have the following format:

Options :

A :

[
   {
      "$unwind": "$reviews"
   },
   {
      "$group": {
         "_id": "$brand",
         "avg_rating": { "$avg": "$reviews.rating" }
      }
   },
   {
      "$match": {
         "avg_rating": { "$gte": 4 }
      }
   }
]

B :

[
   {
      "$group": {
         "_id": "$brand",
         "avg_rating": { "$avg": "$reviews.rating" }
      }
   },
   {
      "$match": {
         "avg_rating": { "$gte": 4 }
      }
   },
   {
      "$project": {
         "brand": "$_id",
         "avg_rating": "$avg_rating",
         "_id": 0
      }
   }
]

C :

[
   {
      "$unwind": "$reviews"
   },
   {
      "$group": {
         "_id": "$brand",
         "avg_rating": { "$avg": "$reviews.rating" }
      }
   },
   {
      "$project": {
         "brand": "$_id",
         "avg_rating": "$avg_rating",
         "_id": 0
      }
   }
]

D :

[
   {
      "$unwind": "$reviews"
   },
   {
      "$group": {
         "_id": "$brand",
         "avg_rating": { "$avg": "$reviews.rating" }
      }
   },
   {
      "$match": {
         "avg_rating": { "$gte": 4 }
      }
   },
   {
      "$project": {
         "brand": "$_id",
         "avg_rating": "$avg_rating",
         "_id": 0
      }
   }
]

Answer: D

Question 3

Which of the following stages do you need to use to randomly select 10 documents from a specific collection?

Options :

A : { $rand: { size: 10 } }

B : { $sample: { get: 10 } }

C : { $sampleRate: { size: 10 } }

D : { $sample: { size: 10 } }

Answer: D

Question 4

You are developing a blogging platform using MongoDB as the database. Each blog post document has a tags array field that holds a list of strings. You are tasked to implement a search functionality that allows users to find blog posts based on the tags. Which of the following MongoDB features would you utilize to implement this functionality efficiently?

Options :

A : Capped Collections

B : Sharding

C : Text Indexes

D : Compound Indexes

E : GridFS

Answer: C

Question 5

In a MongoDB database, you have a collection named orders that contains information about various product orders placed by customers. Each document in the collection has the following structure:

{

"customerID": "",

"orderID": "",

"product": "",

"quantity": ,

"price": ,

"date": "",

"status": ""

}

You are required to write an aggregation query that retrieves all orders placed by customers where the quantity of ordered items is greater than 100 and the status of the order is "delivered". Which of the following $match stages would you use to achieve this? Select the best option.

Options :

A : { "$match": { "quantity": { "$gt": 100 }, "status": "delivered" } }

B : { "$match": { "quantity": { "$lt": 100 }, "status": "delivered" } }

C : { "$match": { "quantity": { "$gt": 100 }, "status": { "$eq": "delivered" } } }

D : { "$match": { "quantity": { "$gte": 100 }, "status": "delivered" } }

Answer: A

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