System Design Roadmap

Reason about scale: the building blocks, the trade-offs, and how to walk through a design.

10 milestones · ~109 hours total

1. 1

   Core concepts

   ~8h

   Latency, throughput, availability, scalability and back-of-envelope estimation.

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2. 2

   Networking and HTTP

   ~8h

   DNS, TCP, HTTP/2, REST vs RPC, WebSockets and long polling.

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3. 3

   Databases and indexing

   ~12h

   SQL vs NoSQL, indexes, query patterns and choosing a data model.

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4. 4

   Caching

   ~8h

   Cache-aside and write-through, eviction policies, CDNs and cache invalidation.

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5. 5

   Load balancing and horizontal scaling

   ~8h

   Stateless services, balancing algorithms, health checks and autoscaling.

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6. 6

   Replication and sharding

   ~12h

   Leader/follower, read replicas, partitioning keys and consistent hashing.

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7. 7

   Queues and asynchronous processing

   ~10h

   Message brokers, at-least-once delivery, idempotency and back-pressure.

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8. 8

   Consistency and the CAP theorem

   ~8h

   Strong vs eventual consistency, quorum reads/writes and where each fits.

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9. 9

   Design classic systems

   ~25h

   URL shortener, rate limiter, chat, news feed, notification service: requirements, API, data, scale.

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10. 10

    Reliability and observability

    ~10h

    Timeouts, retries, circuit breakers, metrics, logs and tracing.

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