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Common Problems
Design a Price Tracking Service like CamelCamelCamel
Evan King
medium
35 min
Understanding the Problem
Functional Requirements
Core Requirements
- Users should be able to view price history for Amazon products (via website or Chrome extension)
- Users should be able to subscribe to price drop notifications with thresholds (via website or Chrome extension)
Below the line (out of scope):
- Search and discover products on the platform
- Price comparison across multiple retailers
- Product reviews and ratings integration
Non-Functional Requirements
The scale and performance requirements for CamelCamelCamel are driven by Amazon's massive product catalog and the need for timely price notifications.
Core Requirements
- The system should prioritize availability over consistency (eventual consistency acceptable)
- The system should handle 500 million Amazon products at scale
- The system should provide price history queries with < 500ms latency
- The system should deliver price drop notifications within 1 hour of price change
Below the line (out of scope):
- Strong consistency for price data
- Real-time price updates (sub-minute)
Here is how your requirements might look on the whiteboard:
CamelCamelCamel Requirements
The Set Up
Planning the Approach
Defining the Core Entities
The API
Data Flow
High-Level Design
1) Users should be able to view price history for Amazon products (via website or Chrome extension)
2) Users should be able to subscribe to price drop notifications with thresholds (via website or Chrome extension)
Potential Deep Dives
1) How do we efficiently discover and track 500 million Amazon products?
2) How do we handle potentially malicious price updates from Chrome extension users?
3) How do we efficiently process price changes and notify subscribed users?
4) How do we serve fast price history queries for chart generation?
Final Design
What is Expected at Each Level?
Mid-level
Senior
Staff+
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