Why indexes are critical for performance in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an index on the 'name' field in MongoDB.

MongoDB

db.collection.createIndex({ name: [1] })

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

A1

Bfalse

Ctrue

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using -1 instead of 1 for ascending index.

Using true or false which are invalid values here.

In MongoDB, creating an index on a field uses 1 for ascending order.

2fill in blank

medium

Complete the query to find documents where 'age' is greater than 30 using an index.

MongoDB

db.collection.find({ age: { [1]: 30 } })

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

A$lt

B$gt

C$eq

D$ne

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt which means less than.

Using $eq which means equals.

The operator $gt means 'greater than' in MongoDB queries.

3fill in blank

hard

Fix the error in the index creation code to ensure it creates a compound index on 'age' ascending and 'score' descending.

MongoDB

db.collection.createIndex({ age: [1], score: [2] })

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

A1

Btrue

C-1

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using true or false instead of 1 or -1.

Using the same order for both fields.

Compound indexes use 1 for ascending and -1 for descending order.

4fill in blank

hard

Fill both blanks to write a query that uses an index to find documents where 'status' is 'active' and 'points' are at least 50.

MongoDB

db.collection.find({ status: [1], points: { [2]: 50 } })

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

A"active"

B$gte

C$lte

D"inactive"

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lte instead of $gte for points.

Using 'inactive' instead of 'active' for status.

The status must be 'active' (a string) and points greater than or equal to 50 uses $gte.

5fill in blank

hard

Fill all three blanks to create a text index on 'title' and 'description' fields and then query documents matching 'mongodb'.

MongoDB

db.collection.createIndex({ [1]: "text", [2]: "text" })
db.collection.find({ $text: { $search: [3] } })

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

Atitle

Bdescription

C"mongodb"

D"database"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong field names for the index.

Not quoting the search string.

Text indexes are created on fields like 'title' and 'description'. The search term must be a string like "mongodb".