High-level design
Topic, then cluster, then study. Recently added is the short list at the top.
Recently added
- 1.SlotWise Reservation Service Incident - HLD Debug & Fix PathA reservation service starts double-booking slots under load. Reproduce, trace isolation and locking choices, fix with the right transaction boundaries, and ship a regression test.
- 1.URL Shortener - Spec, Flask API, SQLite & ConceptsMachine-coding URL shortener hub: Flask+SQLite spec, steps, HTTP contracts, concepts, create/redirect/delete/stats.
- 3.SlotWise - Load Repro & Isolation Decision ChartHow to reproduce the double-book under load, which isolation level still loses without a constraint, and a decision chart for constraint versus row lock versus serializable retries.
- 2.SlotWise - SQLAlchemy Transaction Fix & TestsPartial unique index on active reservations, a transactional reserve that maps IntegrityError to 409, optional SELECT FOR UPDATE on the slot row, and a regression test that spawns concurrent reservers.
- 2.URL Shortener - Flask + SQLite Full Solution, Concurrency & TestsFull Flask+SQLite URL shortener with ownership delete, TTL, atomic hit UPDATE, concurrent hit tests, HTTP status contracts.
- 3.URL Shortener Scale-up HLD - ID Generation, Caching, Sharding & AnalyticsScale-up HLD: ID generation compared, Redis cache-aside, sharding, 301 vs 302, async analytics; cross-link existing pages.
High-level design
HLD interview and machine-coding scale-up: capacity, APIs, data model, caching, sharding, and the path from a single-node solution to production.
SlotWise
3 studies- 1.SlotWise Reservation Service Incident - HLD Debug & Fix PathA reservation service starts double-booking slots under load. Reproduce, trace isolation and locking choices, fix with the right transaction boundaries, and ship a regression test.
- 2.SlotWise - SQLAlchemy Transaction Fix & TestsPartial unique index on active reservations, a transactional reserve that maps IntegrityError to 409, optional SELECT FOR UPDATE on the slot row, and a regression test that spawns concurrent reservers.
- 3.SlotWise - Load Repro & Isolation Decision ChartHow to reproduce the double-book under load, which isolation level still loses without a constraint, and a decision chart for constraint versus row lock versus serializable retries.
URL Shortener
3 studies- 1.URL Shortener - Spec, Flask API, SQLite & ConceptsMachine-coding URL shortener hub: Flask+SQLite spec, steps, HTTP contracts, concepts, create/redirect/delete/stats.
- 2.URL Shortener - Flask + SQLite Full Solution, Concurrency & TestsFull Flask+SQLite URL shortener with ownership delete, TTL, atomic hit UPDATE, concurrent hit tests, HTTP status contracts.
- 3.URL Shortener Scale-up HLD - ID Generation, Caching, Sharding & AnalyticsScale-up HLD: ID generation compared, Redis cache-aside, sharding, 301 vs 302, async analytics; cross-link existing pages.