Why streams handle event logs in Redis - See It in Action

Using Redis Streams to Handle Event Logs

📖 Scenario: You are building a simple event logging system for a web application. Each event represents a user action like login, logout, or page visit. You want to store these events in a way that keeps their order and allows easy retrieval later.

🎯 Goal: Create a Redis stream to store event logs, add events with timestamps, and read them back in order.

📋 What You'll Learn

Create a Redis stream called event_logs

Add three events with exact fields and values to event_logs

Set a maximum length for the stream to keep it manageable

Read all events from event_logs in the order they were added

💡 Why This Matters

🌍 Real World

Event logs are essential for tracking user actions, debugging, and analytics in web applications.

💼 Career

Understanding Redis streams helps backend developers build scalable, real-time logging and messaging systems.

1

Create the Redis stream and add the first event

Use the Redis command XADD to add an event to the stream called event_logs. Add the first event with the fields user set to alice and action set to login. Use * for the ID to let Redis generate the timestamp.

Redis

# Use XADD to add the first event to event_logs
# Your code here

Need a hint?

Remember, XADD adds an entry to a Redis stream. The * lets Redis assign the current timestamp as the ID.

2

Add two more events to the stream

Add two more events to the event_logs stream using XADD. The second event should have user as bob and action as visit_page. The third event should have user as alice and action as logout. Use * for the IDs.

Redis

XADD event_logs * user alice action login
# Add the second event
# Add the third event

Need a hint?

Use XADD again with * for the ID to add each event.

3

Limit the stream length to keep it manageable

Modify the XADD commands to limit the event_logs stream length to a maximum of 100 entries. Use the MAXLEN option with approximate trimming (~).

Redis

XADD event_logs * user alice action login
XADD event_logs * user bob action visit_page
XADD event_logs * user alice action logout
# Add MAXLEN ~ 100 to limit stream length

Need a hint?

The MAXLEN ~ 100 option trims the stream approximately to 100 entries to avoid it growing too large.

4

Read all events from the stream in order

Use the Redis command XRANGE to read all events from the event_logs stream in the order they were added. Use - as the start ID and + as the end ID to get all entries.

Redis

XADD event_logs MAXLEN ~ 100 * user alice action login
XADD event_logs MAXLEN ~ 100 * user bob action visit_page
XADD event_logs MAXLEN ~ 100 * user alice action logout
# Use XRANGE to read all events

Need a hint?

XRANGE event_logs - + returns all entries from the stream in order.