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Lessons (16)

• Caching & Redis

  … 4200, value: "ana" }); await redis.zIncrBy("leaderboard", 50, "bo"); const top10 = await redis.zRangeWithScores("leaderboard", 0, 9, { REV …

• Design a URL Shortener

  Generate durable short links, redirect in milliseconds, prevent abuse and keep analytics off the redirect path. A short …

• Scaling, Load Balancing & Rate Limiting

  … Keep sessions in Redis or in tokens, files in object storage (S3), and state in the database. Scaling …

• Helm, kubectl Cheat Sheet & Best Practices

  … redis bitnami/redis -f my-redis-values.yaml helm rollback my-redis 1 helm uninstall my-redis -n …

• L — Liskov Substitution Principle

  … set(k, v) }; const redisStorage = { get: (k) = redis.get(k), set: (k, v) = redis.set(k, v) }; function …

• Docker & Containers

  … postgres://app:secret@db:5432/shop REDIS URL: redis://cache:6379 depends on: db: { condition: service healthy } cache …

• Authentication, Authorization & API Security

  … App- U: redirect to Google (+ PKCE challenge) U- G: log in + consent G- U: redirect back with ?code …

• SQL vs NoSQL Databases

  … four families mermaid mindmap root((NoSQL)) Document MongoDB Firestore JSON documents Key-value Redis DynamoDB get / set by …

• Flash Sale: 10 Million Buyers, No Oversell

  … A Redis Lua script can gate a hot key, but strict no-oversell still needs a durable owner …

• Premiere-Night Video Streaming

  … Heartbeat progress to Redis for fast resume and persist asynchronously to durable storage. Include a timestamp/sequence so …

• KISS: Keep It Simple, Stupid

  … Profile service] MS1 -- K[(Kafka)] -- MS2 MS3 -- R[(Redis)] end subgraph Simple["✅ 3 users, day one"] direction LR …

• Hash Maps & Sets

  … bat -- K3["key 'abt'"] Real-world uses - Caches (Redis is essentially a giant networked hash map) - Database indexes …

• How a Web Request Works

  … 200 OK, 201 Created, 204 No Content 3xx ↪️ Redirect 301 Moved Permanently, 304 Not Modified 4xx 🙋 Client made …

• Message Queues & RabbitMQ

  … SNS Managed queue / pub-sub Serverless, no ops Redis Streams / BullMQ In-memory streams Lightweight background jobs in …

• Observability: Logs, Metrics & Traces

  … new NodeSDK({ instrumentations: [getNodeAutoInstrumentations()] }).start(); // HTTP, Express, pg, redis, fetch… are now traced automatically SLIs, SLOs and error …

• CQRS & Event Sourcing

  … joined, pre-computed Storage Postgres (transactions) Elasticsearch (search), Redis (fast lookups), a reporting DB Scaling Consistency matters Scale …