Design a Logging for Plaid
Last updated: August 30, 2025
Quick Overview
Design a real-time logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Plaid
System Design
Software Engineer
Plaid
August 30, 2025Software Engineer
Onsite
System Design
Hard
26
6
87 solved
Design a real-time logging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during Onsite at Plaid. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Plaid values engineers who can think about scalability from day one.
What the Interviewer Expects
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
Security and authentication
API design and rate limiting
Caching strategies (local, distributed, CDN)
Failure handling and fault tolerance
Consistency models and replication
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 would you handle schema migrations with zero downtime?
- How do you ensure data consistency across multiple services?
- What would the deployment pipeline look like for this system?
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Requirements
- Functional Requirements:
- Log incoming API requests in real-time, including metadata (timestamp, user ID, request type, response time, etc.).
- Provide a search and filtering API for logs b...
Capacity Estimation
- Incoming Request Rate: Assume Plaid handles 100 million API requests daily, with peak traffic reaching 10 million requests per second.
- Log Entry Size: Average log size is estimated at 1 KB...
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