Why advanced indexing matters in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple index on the 'name' field.

MongoDB

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

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

A1

B-1

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using true or false instead of 1 or -1 causes errors.

Using -1 creates descending index, not ascending.

Using 1 creates an ascending index on the 'name' field, which helps queries sort or filter by name efficiently.

2fill in blank

medium

Complete the code to create 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'

Afalse

B-1

Ctrue

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using true or false instead of 1 or -1.

Reversing directions (e.g. -1 for age, 1 for score).

Use 1 for ascending and -1 for descending. Here, 'age' is ascending (1) and 'score' is descending (-1).

3fill in blank

hard

Fix the error in the index creation by completing the code correctly.

MongoDB

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

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

Aage

B1

Ctrue

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 or true as the field name key.

Leaving the field name blank.

The field name must be a string key, like 'name'. Using 1 or true as a key causes errors.

4fill in blank

hard

Fill both blanks to create a text index on 'description' with unique: true.

MongoDB

db.collection.createIndex({ [1]: 'text' }, { [2]: true })

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

Adescription

Bunique

Cemail

Dsparse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'email' as the text index field instead of 'description'.

Using 'sparse' instead of 'unique' for uniqueness.

The first blank is the field name for the text index, 'description'. The second blank is the option 'unique' set to true to enforce uniqueness on the index.

5fill in blank

hard

Fill all three blanks to create a TTL index on 'createdAt' that expires documents after 3600 seconds.

MongoDB

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

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

AcreatedAt

BexpireAfterSeconds

C3600

Dunique

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'unique' instead of 'expireAfterSeconds'.

Using wrong field name or missing the expiration value.

The field to index is 'createdAt'. The option to set TTL is 'expireAfterSeconds', and the value is 3600 seconds (1 hour).