createIndex method in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an ascending index on the "name" field.

MongoDB

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

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

A1

B-1

C0

D"asc"

Attempts:

3 left

💡 Hint

Common Mistakes

Using -1 instead of 1 for ascending index.

Using 0 which is invalid for index direction.

Using string "asc" which is not accepted.

The value 1 specifies an ascending index in MongoDB.

2fill in blank

medium

Complete the code to create a unique index on the "email" field.

MongoDB

db.users.createIndex({ email: 1 }, { [1]: true })

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

AexpireAfterSeconds

Bsparse

Cunique

Dbackground

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'sparse' which only indexes documents with the field.

Using 'background' which controls index build behavior.

Using 'expireAfterSeconds' which is for TTL indexes.

The unique option ensures no duplicate values in the indexed field.

3fill in blank

hard

Fix the error in the code to create a descending index on the "date" field.

MongoDB

db.events.createIndex({ date: [1] })

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

Aasc

B0

Cdesc

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings like 'asc' or 'desc' which are invalid.

Using 0 which does not specify direction.

Use -1 to specify a descending index in MongoDB.

4fill in blank

hard

Fill both blanks to create a TTL index on the "createdAt" field that expires documents after 3600 seconds.

MongoDB

db.logs.createIndex({ createdAt: [1] }, { [2]: 3600 })

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

A1

BexpireAfterSeconds

Cunique

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using descending index (-1) for TTL which is allowed but less common.

Using 'unique' option which is unrelated to TTL.

The index direction is 1 (ascending), and expireAfterSeconds sets the TTL duration.

5fill in blank

hard

Fill all three blanks to create a compound index on "lastName" (ascending) and "age" (descending) with background building enabled.

MongoDB

db.people.createIndex({ lastName: [1], age: [2] }, { [3]: true })

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

A1

B-1

Cbackground

Dunique

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'unique' instead of 'background' for the option.

Mixing up ascending and descending values.

The compound index uses ascending (1) for lastName, descending (-1) for age, and builds in the background with background: true.