Big news on campus
Serve a sudden surge of reads when thousands of users open the same notification at once.
Kata overview
You do not need to be an expert to start. This kata keeps the stakes low so you can explore trade-offs, adjust the diagram, and see how the system responds.
Context for this system design kata
Serve a sudden surge of reads when thousands of users open the same notification at once. This system design kata keeps the stakes low so you can rehearse trade-offs before taking ideas into production reviews.
Scenario and practice focus
A university sends a notification that prompts tens of thousands of students to open the same detail page within minutes. The notification blast itself is infrequent, but it triggers a sudden, read-heavy surge as students open the app to view details, check updates, and refresh for changes. The read path needs to absorb this traffic without one failure triggering the next, without blowing latency targets, and without runaway costs.
Difficulty: Beginner–Intermediate. Estimated time: 20–35 min. Domain: Education Technology.
Constraints to balance
Operational pressure
- Fully automated - no operator intervention during a burst.
Customer and product constraints
- The burst is short-lived. Don't over-spend on always-on capacity.
Scenarios to explore in the simulator
- Serve notification detail pages under the p95 latency target during post-blast surges.
- Prevent read amplification from overwhelming core data stores.
- Keep costs steady under sudden, short-lived spikes.
- Avoid retry and refresh storms when users perceive slowness.
Learning outcomes
- Reason about post-notification read surges using chaptered playback.
- Design read paths that remain stable under extreme, short-lived RPS.
- Isolate core data stores from read amplification.
- Evaluate cache behaviour, replica lag, and recovery across time.
Give it a try!