Unique visitor tracking with sets in Redis - Mini Project: Build & Apply

Unique Visitor Tracking with Sets in Redis

📖 Scenario: You run a website and want to track unique visitors each day. You will use Redis sets to store visitor IDs because sets automatically keep only unique values.

🎯 Goal: Build a Redis data structure that stores unique visitor IDs for a specific day and allows you to count how many unique visitors came that day.

📋 What You'll Learn

Create a Redis set key for visitors on a specific date

Add visitor IDs to the set

Use a variable for the date key

Count the number of unique visitors using the set's cardinality

💡 Why This Matters

🌍 Real World

Websites and apps often need to count unique visitors daily to understand traffic and user engagement.

💼 Career

Knowing how to use Redis sets for unique tracking is useful for backend developers and data engineers working with real-time analytics.

1

Create a Redis set key for today's visitors

Create a Redis key called visitors:2023-06-01 to represent the set of unique visitors for June 1, 2023. Use the Redis command SADD to add visitor IDs user1, user2, and user3 to this set.

Redis

# Use SADD to add 'user1', 'user2', and 'user3' to the set 'visitors:2023-06-01'
# Your code here

Need a hint?

Use SADD followed by the key name and the visitor IDs separated by spaces.

2

Use a variable for the date key

Create a Redis variable called date_key and set it to visitors:2023-06-01. This variable will hold the key name for the visitor set.

Redis

SADD visitors:2023-06-01 user1 user2 user3
# Set the variable date_key to 'visitors:2023-06-01'
# Your code here

Need a hint?

Use the SET command to create a variable holding the key name.

3

Add more visitor IDs using the date_key variable

Use the SADD command with the variable date_key to add visitor IDs user4 and user5 to the set.

Redis

SADD visitors:2023-06-01 user1 user2 user3
SET date_key visitors:2023-06-01
# Add 'user4' and 'user5' to the set using SADD and the variable date_key
# Your code here

Need a hint?

Use SADD with the key name to add new visitors. Redis CLI does not support variable substitution like $date_key.

4

Count the number of unique visitors

Use the SCARD command with the variable date_key to get the count of unique visitors for June 1, 2023.

Redis

SADD visitors:2023-06-01 user1 user2 user3
SET date_key visitors:2023-06-01
SADD visitors:2023-06-01 user4 user5
# Use SCARD with the key to count unique visitors
# Your code here

Need a hint?

SCARD returns the number of unique elements in a set.