Design an E-Commerce Product Catalog Service
We want to build a high-performance product catalog service for an e-commerce platform. The service provides product details and category listings to shoppers while accommodating updates from merchants.
This brief is incomplete on purpose, as it would be in a real interview. Ask the interviewer about the users, the features, the targets and the traffic. Whatever you uncover is added below.
- Shoppers must be able to view detailed product information using a product ID.
- Shoppers must be able to browse products filtered by category and brand.
- Catalog updates
- Read latency target
- Read availability target
- Daily active users
- User activity volume
- Update volume
- Product payload size
- High-level system architecture showing client requests, application services, caching layer, and primary database.
- Data model for storing product details and category mappings.
- Detailed request flow diagram for catalog reads and cache updates/invalidations.
Demonstrates a clean cache-aside or read-through caching topology (e.g. Redis) that serves the vast majority of product reads to achieve low latency.
Defines an explicit invalidation or update strategy (e.g. CDC, event bus pub/sub, or write-through) ensuring product updates reflect in the cache within the required SLA without serving stale data indefinitely.
Selects an appropriate primary datastore (e.g. Document DB or Relational DB with JSON support) suitable for flexible product attributes and reliable persistent writes.
Addresses resilience strategies such as read replicas, multi-node caching clusters, and methods to handle high concurrency on popular items.
Every functional requirement in the brief is visibly served by something on the board, and the non-functional targets are addressed rather than ignored.
Components are labelled, data flows are drawn as connections between them, and the direction of each flow is unambiguous.
Focus on the read path caching topology, cache invalidation strategy, and database storage choice. Shopping cart management, payment processing, checkout flows, and search indexing algorithms are out of scope.