TTL-based expiry in Redis - Mini Project: Build & Apply

TTL-based Expiry in Redis

📖 Scenario: You are managing a Redis cache for a web application that stores temporary session data. To keep the cache clean and efficient, you want to set expiration times on session keys so that old sessions are automatically removed.

🎯 Goal: Build a Redis setup where you create session keys with values, configure expiration times (TTL), and verify that keys expire as expected.

📋 What You'll Learn

Create a Redis key named session:user123 with the value active

Set a TTL (time to live) of 120 seconds on the session:user123 key

Retrieve the TTL of the session:user123 key to confirm it is set

Use the EXPIRE command to update the TTL to 60 seconds

💡 Why This Matters

🌍 Real World

Setting TTLs on cache or session keys helps automatically remove stale data, keeping Redis memory usage efficient.

💼 Career

Many backend developers and DevOps engineers use Redis TTL features to manage cache lifecycles and session expiration in real applications.

1

Create a session key with a value

Use the SET command to create a Redis key called session:user123 with the value active.

Redis

# Use SET command to create the key
# Your code here

Need a hint?

The SET command stores a key with a value in Redis.

2

Set a TTL of 120 seconds on the session key

Use the EXPIRE command to set a TTL of 120 seconds on the key session:user123.

Redis

SET session:user123 active
# Use EXPIRE command to set TTL to 120 seconds
# Your code here

Need a hint?

The EXPIRE command sets the time to live for a key in seconds.

3

Check the TTL of the session key

Use the TTL command to retrieve the remaining time to live of the key session:user123.

Redis

SET session:user123 active
EXPIRE session:user123 120
# Use TTL command to check the expiry time
# Your code here

Need a hint?

The TTL command returns the remaining seconds before the key expires.

4

Update the TTL to 60 seconds

Use the EXPIRE command again to update the TTL of session:user123 to 60 seconds.

Redis

SET session:user123 active
EXPIRE session:user123 120
TTL session:user123
# Use EXPIRE command to update TTL to 60 seconds
# Your code here

Need a hint?

You can reset the TTL of a key anytime using the EXPIRE command.