Design a high-throughput Logging System
Last updated: February 20, 2026
Quick Overview
Design a high-throughput logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Mastercard
System Design
Product Manager
Mastercard
February 20, 2026Product Manager
System Design Round
System Design
Medium
49
12
2,838 solved
Design a high-throughput logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Mastercard asks this during the System Design Round to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Consistency models and replication
Database selection and data modeling
Load balancing and horizontal scaling
Caching strategies (local, distributed, CDN)
Requirements gathering and capacity estimation
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How do you ensure data consistency across multiple services?
- How would you optimize costs as the system scales?
- How would you handle a region-wide outage?
- What happens if one of your database nodes goes down?
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Requirements
Functional Requirements
- High-throughput logging: The system should handle millions of log requests per second (QPS) from various Mastercard services, ensuring minimal latency.
- **Log stor...
Capacity Estimation
Back-of-Envelope Calculations
- Log Volume: Assume Mastercard processes approximately 1 billion transactions per day. Each transaction generates an average of 10 log entries.
- Total Logs:...
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