Functional Requirements (what the system must do)

1. Track ad clicks in real time — when a user on a website clicks an ad, record the event with ad_id, user_id (cookie), timestamp, and click metadata (IP, browser, referrer).
2. Aggregate clicks by time window — produce click counts per ad over windows like minute/hour/day. This powers the dashboards advertisers see.
3. Support demographic & contextual breakdowns — slice the data by age, gender, geo location, and the website where the ad appeared, so advertisers can see who clicked and where.

Non-Functional Requirements (how it behaves)

1. Real-time / low latency — advertisers make live budget decisions, so click counts must update in seconds, not hours.
2. Scalability — handle millions of clicks per day (or hour) across many ad placements — needs horizontal scaling.
3. Eventual consistency is acceptable — losing a click or showing a slightly stale count for a few seconds is fine; ACID transactions aren't needed. Availability matters more than strict consistency.

A good framing for the interview: high write throughput + near-real-time reads + a handful of aggregation dimensions is what drives most of your later design decisions.

Want to paste that into the Requirements panel and I'll review it, or would you like to go deeper on one of these (e.g., why eventual consistency is the right call here)?

Capacity Estimation

API Design

POST - Generate Events

/api/v1/event

GET - Get statistics by time/url

/api/v1/stats/uid|tid

High-Level Design

Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.

Database Design

Define the data model. Identify the main entities, their attributes, and relationships. Consider the choice of database type (SQL vs NoSQL) and justify your decision based on access patterns...

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.