System Design Case Studies

Introductory section map with 30 cases: from infrastructure primitives to product systems with different architectural constraints.

Classic task: base62 encoding, ID generation (Snowflake), caching strategy and 301 vs 302 redirect.

Classic task: Token Bucket, Sliding Window, Redis + Lua scripts, distributed rate limiting.

Push notifications (APNs, FCM), email, SMS: device token management, delivery guarantees, retry patterns.

Classic task: routing, authentication, rate limiting, load balancing, request/response transformation.

Classic problem: Push vs Pull CDN, cache invalidation, Origin Shield, geographic routing.

Classic task: inverted index, web crawling, ranking (BM25, PageRank), distributed search.

Classic task: candidate generation, ranking, cold start, feature store, exploration/exploitation, and recommendation quality metrics.

Classic task: feature pipelines, model registry, offline/online parity, rollout safety, and drift monitoring.

Classic case on designing the Feature Store + Model Serving pair for an ML platform with online/offline parity, point-in-time correctness, and training-serving skew controls.

Classic task: distributed URL frontier, politeness/robots.txt, deduplication, re-crawl and ingestion into the search index.

Classic task: metadata/data separation, durability (11 nines), erasure coding, multipart upload.

Classic task: master/data nodes, block replication, metadata management, recovery and high throughput I/O.

Classic task: WebSocket, real-time messaging, presence, groups, synchronization and scaling.

Public interview at C++ Russia 2022: transcoding, fan-out strategies, CDN and asynchronous processing.

Classic problem: feed generation, fanout on write vs read, trending topics, search.

Experiment system design: hash-based assignment, layer architecture, event streaming and statistical analysis.

Classic task: geo-index, nearby search, ranking, caching, regional sharding and latency-budget for a map.

Classic task: authoritative game server, matchmaking, state sync, anti-cheat and low-latency networking.

Public interview at C++ Russia 2023: distributed locking and protection against double booking.

Public interview at ArchDays 2022: overbooking, inventory model, competition and scaling.

Classic task: geo-search, availability calendar, dynamic pricing, two-sided marketplace.

Classic problem: real-time location, driver-rider matching, ETA calculation, surge pricing.

Classic task: idempotency, authorization/capture/refund, payment orchestration, ledger and reconciliation.

Classic task: partitioning, replication, quorum read/write, anti-entropy and hot partition mitigation.

Classic task: partitioned log, consumer groups, retry/DLQ, delivery semantics and backpressure.

Classic task: stream ingestion, dedupe, windowed aggregations, freshness SLA and billing accuracy.

Classic task: SLO-driven social platform architecture, failure isolation, graceful degradation and observability.

Classic task: RBAC/ABAC/ReBAC, policy decision point, audit trail and cache invalidation.

Classic task: analytical serving layer, pre-aggregations, metric consistency and data freshness.

Classic task: delay-tolerant networking, store-and-forward transport, autonomous nodes, and eventual synchronization.