Design a event-driven Notification System

Last updated: May 23, 2026

Quick Overview

Design a event-driven notification system handling millions of requests. Discuss consistency, availability, and performance trade-offs.

Walmart
ML System Design
Machine Learning Engineer
Walmart
May 23, 2026
Machine Learning Engineer
Onsite
ML System Design
Easy

578

10

4,813 solved


Design a event-driven notification system handling millions of requests. Discuss consistency, availability, and performance trade-offs.

How to Approach This
  1. Start by mapping the business objective to a concrete ML objective and metric.
  2. Cover the full pipeline: data collection, feature engineering, model selection, training, serving.
  3. Discuss online vs offline evaluation. Plan an A/B test to validate real-world impact.
  4. Address the serving latency budget and whether batch or real-time inference is needed.
  5. Think about the data flywheel: how user feedback improves the model over time.
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Sample Answer
Problem Formulation

The goal is to design an event-driven notification system for Walmart that can efficiently handle millions of requests for sending notifications (e.g., promotions, order updates, alerts). This maps to...

Data & Features

The system will require various data sources:

  • User Data: Profiles including demographics, past interactions, preferences, and purchase history.
  • Event Data: Timestamped logs of user actio...

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