Compound index and field order in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a compound index on fields 'name' and 'age'.

MongoDB

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

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

Aage

Bemail

Caddress

Dphone

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field not intended for the index like 'email'.

Forgetting to specify the field name.

The compound index is created on 'name' and 'age'. The order matters for query optimization.

2fill in blank

medium

Complete the code to find documents where 'name' is 'Alice' and 'age' is 30 using the compound index.

MongoDB

db.users.find({ name: 'Alice', [1]: 30 })

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

Aphone

Baddress

Cemail

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using a field not in the index for filtering.

Misspelling the field name.

The query filters on 'name' and 'age' fields, matching the compound index fields.

3fill in blank

hard

Fix the error in the compound index creation by choosing the correct field order.

MongoDB

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

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

Aaddress

Bemail

Cage

Dphone

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping field order incorrectly.

Using fields not intended for the index.

The correct order is 'age' then 'name' if the index is intended that way; here, 'age' must be the first field.

4fill in blank

hard

Fill both blanks to create a compound index on 'city' ascending and 'score' descending.

MongoDB

db.players.createIndex({ [1]: 1, [2]: -1 })

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

Acity

Bscore

Cage

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up field names.

Using wrong sort order values.

The index is on 'city' ascending (1) and 'score' descending (-1).

5fill in blank

hard

Fill all three blanks to create a compound index on 'category' ascending, 'price' ascending, and 'rating' descending.

MongoDB

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

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

Acategory

Bprice

Crating

Dstock

Attempts:

3 left

💡 Hint

Common Mistakes

Incorrect field order.

Wrong sort directions.

The compound index includes 'category' and 'price' ascending, and 'rating' descending.