Topics / High-level design

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.

Common tags: hld, url-shortener, system-design, machine-coding

• High-level designOct 2026

  URL Shortener Scale-up HLD - ID Generation, Caching, Sharding & Analytics

  Cluster · URL Shortener

  Scale-up HLD: ID generation compared, Redis cache-aside, sharding, 301 vs 302, async analytics; cross-link existing pages.

  • hld
  • url-shortener
  • flask
  • sqlite
  • system-design
  • interview
  • machine-coding
  Open study →
• High-level designOct 2026

  URL Shortener - Flask + SQLite Full Solution, Concurrency & Tests

  Cluster · URL Shortener

  Full Flask+SQLite URL shortener with ownership delete, TTL, atomic hit UPDATE, concurrent hit tests, HTTP status contracts.

  • hld
  • url-shortener
  • flask
  • sqlite
  • system-design
  • interview
  • machine-coding
  Open study →
• High-level designOct 2026

  SlotWise - SQLAlchemy Transaction Fix & Tests

  Cluster · SlotWise

  Partial 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.

  • hld
  • reservations
  • sqlalchemy
  • postgres
  • isolation
  • interview
  • incident
  Open study →
• High-level designOct 2026

  SlotWise - Load Repro & Isolation Decision Chart

  Cluster · SlotWise

  How 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.

  • hld
  • reservations
  • sqlalchemy
  • postgres
  • isolation
  • interview
  • incident
  Open study →
• High-level designOct 2026

  URL Shortener - Spec, Flask API, SQLite & Concepts

  Cluster · URL Shortener

  Machine-coding URL shortener hub: Flask+SQLite spec, steps, HTTP contracts, concepts, create/redirect/delete/stats.

  • hld
  • url-shortener
  • flask
  • sqlite
  • system-design
  • interview
  • machine-coding
  Open study →
• High-level designOct 2026

  SlotWise Reservation Service Incident - HLD Debug & Fix Path

  Cluster · SlotWise

  A 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.

  • hld
  • reservations
  • sqlalchemy
  • postgres
  • isolation
  • interview
  • incident
  Open study →