⏱ 6 min read Core Entities Post: post_id, user_id, content, media_urls[], platforms[] (TWITTER, INSTAGRAM, LINKEDIN, FACEBOOK), scheduled_at (UTC), status (DRAFT, SCHEDULED, PUBLISHING, PUBLISHED, FAILED), […] Read article

⏱ 6 min read Why Distributed Locks? A mutex works within a single process. A database row lock works within a single database. When Read article

⏱ 6 min read Core Entities Order: order_id, customer_id, restaurant_id, driver_id, items[], total_cents, status, placed_at, estimated_delivery_at. OrderStatus (state machine): PLACED -> CONFIRMED -> PREPARING Read article

⏱ 6 min read The Problem with Distributed Transactions In a monolith with a single database, ACID transactions guarantee atomicity: either all operations succeed Read article

⏱ 6 min read The Core Challenge A flash sale sells a limited quantity (e.g., 1000 units) at a discounted price for a short Read article

⏱ 5 min read What Is a Config Management Service? A configuration management service stores application settings that need to change without a code Read article

⏱ 5 min read Core Entities Provider: provider_id, name, timezone, working_hours (JSONB: {“MON”: [“09:00″,”17:00”], …}), slot_duration_minutes (e.g., 30). Appointment: appointment_id, provider_id, client_id, start_time (UTC), Read article

⏱ 6 min read What Is a Geo-Proximity Service? A geo-proximity service finds entities (businesses, drivers, users) near a given location. Core operations: store Read article

⏱ 6 min read Core Entities Content: content_id, type (TEXT, IMAGE, VIDEO), author_id, platform, raw_content / storage_url, created_at. ModerationDecision: decision_id, content_id, verdict (APPROVED, REMOVED, Read article

⏱ 5 min read Core Entities Driver: driver_id, current_location (lat/lng), status (AVAILABLE, ON_TRIP, OFFLINE), vehicle_type, rating. Rider: rider_id, payment_method_id, rating. Trip: trip_id, rider_id, driver_id, Read article

⏱ 6 min read What Is Event-Driven Architecture? Event-Driven Architecture (EDA) decouples services by having them communicate through events rather than direct API calls. Read article

⏱ 7 min read Requirements Functional: send notifications via multiple channels (push, email, SMS, in-app), support notification templates with variable substitution, allow users to Read article

⏱ 7 min read The Video Upload and Processing Problem YouTube processes 500 hours of video every minute. Each uploaded video must be transcoded Read article