What is MongoDB - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What type of database is MongoDB?

MongoDB is best described as which type of database?

A A document-oriented NoSQL database that stores data in JSON-like documents

B A relational database that uses tables and rows

C A graph database that stores data as nodes and edges

D A key-value store that only supports simple key-value pairs

💡 Hint

Think about how MongoDB stores data compared to traditional databases.

MongoDB stores data as flexible JSON-like documents, making it a document-oriented NoSQL database, unlike relational databases that use tables.

🧠 Conceptual

intermediate

Which feature is a key advantage of MongoDB?

What is a main advantage of using MongoDB over traditional relational databases?

A It requires a fixed schema before storing data

B It cannot scale horizontally across servers

C It only supports SQL queries

D It supports flexible schemas allowing different documents to have different structures

💡 Hint

Think about how MongoDB handles data structure changes.

MongoDB allows flexible schemas, so documents in the same collection can have different fields and structures, unlike fixed schemas in relational databases.

❓ query_result

advanced

What is the output of this MongoDB query?

Given a collection 'users' with documents: {name: 'Alice', age: 30}, {name: 'Bob', age: 25}, what does this query return? db.users.find({age: {$gt: 27}})

MongoDB

db.users.find({age: {$gt: 27}})

A [{name: 'Alice', age: 30}]

B [{name: 'Bob', age: 25}]

C []

D SyntaxError

💡 Hint

Look for users with age greater than 27.

The query finds documents where age is greater than 27, so only Alice's document matches.

📝 Syntax

advanced

Which MongoDB query syntax correctly updates a user's age?

You want to update the age of the user named 'Bob' to 28. Which query is correct?

A db.users.modify({name: 'Bob'}, {$set: {age: 28}})

B db.users.update({name: 'Bob'}, {age: 28})

C db.users.updateOne({name: 'Bob'}, {$set: {age: 28}})

D db.users.updateOne({name: 'Bob'}, {age: 28})

💡 Hint

Remember the correct update operator and method name.

The correct syntax uses updateOne with a filter and the $set operator to update fields.

❓ optimization

expert

How to improve query performance in MongoDB?

You have a large collection and queries on the 'email' field are slow. What is the best way to improve query speed?

A Increase the RAM of the server without changing the database

B Create an index on the 'email' field

C Use $where with JavaScript to filter emails

D Store emails in a separate collection

💡 Hint

Indexes help databases find data faster.

Creating an index on the 'email' field allows MongoDB to quickly locate documents matching queries on that field.