Exploration ·
Pull the plug on a database halfway through a write and it comes back with every committed transaction and none of the half-finished ones. How? Follow a write through the log, the buffer pool and the disk, compare B+trees with LSM-trees, watch compaction, and then see the other half of the promise — what concurrent transactions are allowed to see — with real PostgreSQL and SQLite running between the paragraphs.
Tool ·
Practise big-tech style system design interviews: a paced 45- or 60-minute framework with a mock interviewer, random questions and a self-scoring rubric, a back-of-the-envelope estimator, 38 reference architectures (likes, web search, webhooks, group chat, Kafka- and Dynamo-style stores, maps, a matching engine and more) as clickable diagrams with model deep-dive answers and interview cards, a live simulation of each one you can overload and break, a searchable question bank with a compare view, runnable building blocks (rate limiters, consistent hashing, Snowflake IDs, Bloom filters, fencing tokens, the outbox pattern and more) with Python, Go and Java versions, and trade-off cards.