HLD concepts, deep dives, and design patterns — my personal study notes
Distributed event streaming, partitions, consumer groups, replication, and real-world use cases.
In-memory data store, data structures, persistence, caching patterns, pub/sub, and Lua scripting.
Distributed search engine, inverted index, shards, mappings, query DSL, and aggregations.
Probabilistic data structures for set membership — false positives, hash functions, and 15 design use cases.
Cassandra vs PostgreSQL vs DynamoDB — when to use each, trade-offs, consistency models.
Sharding, partitioning, write-ahead logs, CQRS, and strategies for write-heavy workloads.
Read replicas, caching strategies, CDNs, database indexing, and denormalization patterns.
When to use serverless functions vs container orchestration — cost, cold starts, scalability trade-offs.
Back-of-envelope estimation, latency numbers every engineer should know, throughput reference tables.
OSI model, TCP/IP, DNS, HTTP/HTTPS, load balancing, CDN, and common interview networking questions.
Processes vs threads, scheduling, memory management, deadlocks, and concurrency primitives.
WebSockets, Kafka fan-out, Cassandra message store, offline delivery, presence, and group chat at scale.
Event-driven microservices, order state machine, cart in Redis, real-time tracking, and background job patterns.
Fan-out on write vs read, celebrity problem, Redis sorted set timelines, Snowflake IDs, and ML ranking.
Pre-signed S3 uploads, HLS transcoding pipeline, CDN edge serving, adaptive bitrate, and view count at scale.
Task queues, Kafka fan-out, DAG workflows, exponential backoff, DLQ, idempotency, and real-world patterns.
Race conditions, Kafka partition serialisation, optimistic locking, Redis Lua atomicity, and auction-end edge cases.
Real-time fan-out to millions of viewers, Redis channel-per-video, WebSocket delivery, Kafka spike buffering, and hot video scaling.
Distributed transactions across microservices — choreography vs orchestration, compensating transactions, and the outbox pattern.
Persistent bidirectional TCP, handshake, scaling with sticky sessions and Redis pub/sub, and 8 common production problems.