Why performance tuning matters in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find all documents in the 'users' collection.

MongoDB

db.users.[1]()

Drag options to blanks, or click blank then click option'

Afind

Binsert

Cupdate

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using insert() instead of find()

Using update() when you want to read data

The find() method retrieves documents from a collection. Here, it fetches all documents from 'users'.

2fill in blank

medium

Complete the code to find users older than 25.

MongoDB

db.users.find({ age: { [1]: 25 } })

Drag options to blanks, or click blank then click option'

A$gt

B$eq

C$ne

D$lt

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt (less than) instead of $gt

Using $eq which means equal

The $gt operator means 'greater than'. So this query finds users with age greater than 25.

3fill in blank

hard

Fix the error in the query to find users with name 'Alice'.

MongoDB

db.users.find({ name: [1] })

Drag options to blanks, or click blank then click option'

A{name: 'Alice'}

BAlice

C"Alice"

D'Alice'

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the string

Using an object instead of a string

String values in MongoDB queries must be quoted. Using 'Alice' correctly specifies the string.

4fill in blank

hard

Fill both blanks to find users with age between 20 and 30.

MongoDB

db.users.find({ age: { [1]: 20, [2]: 30 } })

Drag options to blanks, or click blank then click option'

A$gte

B$lt

C$lte

D$gt

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gt and $lt which exclude 20 and 30

Mixing up the operators

$gte means 'greater than or equal to' and $lte means 'less than or equal to'. Together they find ages between 20 and 30 inclusive.

5fill in blank

hard

Fill all three blanks to create an index on the 'email' field in ascending order.

MongoDB

db.users.createIndex({ [1]: [2] }, { unique: [3] })

Drag options to blanks, or click blank then click option'

Aemail

B1

Ctrue

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of 1 for ascending

Setting unique to false or 0

Creating an index on 'email' with ascending order (1) and setting unique to true ensures no duplicate emails.