LTRIM for list capping in Redis - Mini Project: Build & Apply

LTRIM for List Capping in Redis

📖 Scenario: You are managing a Redis list that stores recent user actions on a website. To keep the list from growing too large and using too much memory, you want to keep only the latest 5 actions.

🎯 Goal: Build a Redis command sequence that adds user actions to a list and then trims the list to keep only the latest 5 entries using LTRIM.

📋 What You'll Learn

Create a Redis list called user_actions.

Add 7 specific actions to the user_actions list using LPUSH.

Use LTRIM to keep only the latest 5 actions in the list.

Verify the list contains exactly the 5 most recent actions.

💡 Why This Matters

🌍 Real World

Websites and apps often track recent user actions or events in Redis lists to quickly access the latest data without storing too much history.

💼 Career

Knowing how to cap Redis lists is important for backend developers and DevOps engineers to manage memory and performance in real-time applications.

1

Create the Redis list and add 7 actions

Use the LPUSH command to add these exact actions to the list called user_actions in this order: "login", "view_page", "click_ad", "logout", "login", "purchase", "logout".

Redis

# Use LPUSH to add the 7 actions to user_actions list
# Your code here

Need a hint?

Use LPUSH with the list name user_actions and add all 7 actions in one command.

2

Set the maximum list size to 5

Create a variable called max_size and set it to 5 to represent the maximum number of actions to keep in the list.

Redis

LPUSH user_actions "login" "view_page" "click_ad" "logout" "login" "purchase" "logout"
# Set max_size to 5
# Your code here

Need a hint?

Just assign the number 5 to a variable named max_size.

3

Trim the list to keep only the latest 5 actions

Use the LTRIM command on the user_actions list to keep only the elements from index 0 to max_size - 1.

Redis

LPUSH user_actions "login" "view_page" "click_ad" "logout" "login" "purchase" "logout"
max_size=5
# Use LTRIM to keep only the latest 5 actions
# Your code here

Need a hint?

Use LTRIM user_actions 0 4 because list indexes start at 0 and you want 5 items total.

4

Verify the list contains only the latest 5 actions

Use the LRANGE command on user_actions from index 0 to -1 to get all elements and confirm the list has exactly 5 actions.

Redis

LPUSH user_actions "login" "view_page" "click_ad" "logout" "login" "purchase" "logout"
max_size=5
LTRIM user_actions 0 4
# Use LRANGE to get all elements from user_actions
# Your code here

Need a hint?

Use LRANGE user_actions 0 -1 to get the full list contents.