TTL indexes for auto-expiry in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a TTL index on the 'createdAt' field that expires documents after 3600 seconds.

MongoDB

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

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

A3600

B60

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or negative numbers which disable TTL expiration.

Confusing minutes with seconds.

The expireAfterSeconds option sets the time in seconds after which documents expire. Here, 3600 seconds means documents expire after one hour.

2fill in blank

medium

Complete the code to create a TTL index on the 'lastModified' field that expires documents after 86400 seconds (1 day).

MongoDB

db.collection.createIndex({ [1]: 1 }, { expireAfterSeconds: 86400 })

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

AcreatedAt

BlastModified

Ctimestamp

DexpireAt

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong field name for the TTL index.

Confusing the field with other date fields.

The TTL index must be created on the field that stores the date to expire documents. Here, it's lastModified.

3fill in blank

hard

Fix the error in the TTL index creation code by filling the blank with the correct option.

MongoDB

db.collection.createIndex({ expireAt: 1 }, { [1]: 3600 })

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

AexpireAfter

BexpireAfterMinutes

CexpireAfterSeconds

DexpireSeconds

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect option names like 'expireAfterMinutes' or 'expireSeconds'.

Misspelling the option name.

The correct option name for TTL expiration time is expireAfterSeconds. Other options are invalid and cause errors.

4fill in blank

hard

Fill both blanks to create a TTL index on 'timestamp' field that expires documents after 7200 seconds (2 hours).

MongoDB

db.collection.createIndex({ [1]: [2] }, { expireAfterSeconds: 7200 })

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

Atimestamp

B1

C-1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using -1 or 0 as index direction which is invalid here.

Using wrong field names.

The TTL index must be created on the date field with ascending order (1). Negative or zero values are invalid for index direction.

5fill in blank

hard

Fill all three blanks to create a TTL index on 'expireAt' field with ascending order and expiration after 1800 seconds (30 minutes).

MongoDB

db.collection.createIndex({ [1]: [2] }, { [3]: 1800 })

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

AexpireAt

B1

CexpireAfterSeconds

Dtimestamp

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong field names or index directions.

Using incorrect option names for expiration.

The TTL index is created on the 'expireAt' field with ascending order (1) and the option 'expireAfterSeconds' sets the expiration time.