DEL and UNLINK for deletion in Redis - Mini Project: Build & Apply

Using DEL and UNLINK Commands in Redis for Key Deletion

📖 Scenario: You are managing a Redis database that stores user session data for a web application. Sometimes, you need to delete session keys to free up memory or remove expired sessions.

🎯 Goal: Learn how to delete keys in Redis using the DEL and UNLINK commands. You will create keys, set a configuration variable, delete keys using both commands, and understand the difference between them.

📋 What You'll Learn

Create keys with specific names and values

Set a configuration variable to control deletion behavior

Use the DEL command to delete keys synchronously

Use the UNLINK command to delete keys asynchronously

💡 Why This Matters

🌍 Real World

Web applications often store session data in Redis. Efficiently deleting expired or unused sessions helps maintain performance and memory usage.

💼 Career

Understanding DEL and UNLINK commands is important for database administrators and backend developers managing Redis databases to optimize resource usage.

1

Create Redis keys for user sessions

Create three Redis keys named session:1001, session:1002, and session:1003 with values user1, user2, and user3 respectively using the SET command.

Redis

# Use SET command to create keys
# Your code here

Need a hint?

Use the SET command followed by the key name and value.

2

Set a configuration variable for lazy deletion

Set the Redis configuration variable lazyfree-lazy-eviction to yes using the CONFIG SET command to enable asynchronous deletion for eviction.

Redis

SET session:1001 user1
SET session:1002 user2
SET session:1003 user3
# Use CONFIG SET to enable lazyfree-lazy-eviction
# Your code here

Need a hint?

Use CONFIG SET followed by the variable name and value.

3

Delete keys synchronously using DEL

Use the DEL command to delete the keys session:1001 and session:1002 synchronously.

Redis

SET session:1001 user1
SET session:1002 user2
SET session:1003 user3
CONFIG SET lazyfree-lazy-eviction yes
# Use DEL to delete session:1001 and session:1002
# Your code here

Need a hint?

Use DEL followed by the keys you want to delete.

4

Delete keys asynchronously using UNLINK

Use the UNLINK command to delete the key session:1003 asynchronously.

Redis

SET session:1001 user1
SET session:1002 user2
SET session:1003 user3
CONFIG SET lazyfree-lazy-eviction yes
DEL session:1001 session:1002
# Use UNLINK to delete session:1003 asynchronously
# Your code here

Need a hint?

Use UNLINK followed by the key you want to delete asynchronously.