Design ad click aggregator and file sync service
Quick Overview
This question evaluates system design competencies in building scalable, reliable distributed services—covering high-throughput event ingestion and aggregation, real-time analytics, idempotency and out-of-order handling for ad click processing, and cloud file storage, synchronization, versioning and secure sharing for a Dropbox-like service, and it falls under the System Design domain. It is commonly asked to assess architectural thinking about APIs, data models, major components, scaling strategies and operational trade-offs, and focuses primarily on conceptual architectural understanding with practical application constraints like latency, consistency, throughput, storage efficiency and security.
You have two system design prompts.
1) Design an ads click aggregation system
Design a service that ingests ad click events at very high QPS and supports aggregated analytics.
Functional requirements
- Ingest click/impression events (at least clicks; optionally impressions) from multiple frontends.
-
Provide near-real-time aggregates such as:
-
clicks per
ad_id/campaign_id/advertiser_id - breakdown by time window (e.g., per minute, per hour, per day)
- optionally by country/device
-
clicks per
- Support querying these aggregates via an API (and/or dashboard).
Non-functional requirements
- High write throughput; scalable horizontally.
- Handle duplicates and retries (idempotency).
- Handle late/out-of-order events.
- Clearly define consistency/latency targets (e.g., “within 1–5 minutes”).
2) Design a file storage + sync service (Dropbox-like)
Design a cloud file sync product where users can upload files, keep folders in sync across devices, and share files.
Functional requirements
- Upload/download files and list folders.
- Sync changes across multiple devices (near real-time).
- Versioning (recover older versions) and deletion/restore.
- Sharing via link and/or ACL-based sharing.
Non-functional requirements
- Large files support (chunking/resumable upload).
- Efficient storage (dedup/content-addressing acceptable).
- Security (authn/authz, encryption).
- High availability and scalability.
For both prompts, explain APIs, data model, major components, scaling strategy, and key trade-offs.