Step 1: Problem Statement Analysis (Netflix)

Core Product Features

A global video streaming platform like Netflix coordinates:

1. User Accounts & Subscriptions: Core billing accounts associated with tiered monthly subscription plans (Basic, Standard, Premium) that limit screen counts.
2. Multi-Profile Personalization: Allowing up to 5 user profiles per account, each with private watchlists, distinct rating histories, and customized age settings.
3. Complex Catalog Hierarchy: Handling both stand-alone Movies and episodic TV Shows (which have multiple Seasons, each having multiple Episodes).
4. Real-time Playback State Tracker: Saving watch progress (last playback position in seconds, completed flag) frequently to allow "Resume Playing" across devices.
5. CDN Node Assignment (Open Connect): Mapping movie streams to regional edge caching servers to reduce traffic latency.

⚠️ Key Technical Challenges

• Episodic vs. Feature Content Hierarchy: Designing a clean relational schema that represents both 10-season TV Shows and a single-release Movie without creating redundant fields or tables.
• Ultra-High Concurrency Stream Tracking: Playback state events are sent every 10 seconds. The database must sustain massive write operations to update last_watched_position fields without blocking other database operations.
• Concurrent Screen Count Checks: Validating plan limits (e.g., maximum of 4 active screens for Premium) in real time before allowing a profile to initiate a new video stream.

Business Rules

• Standard sub-profiles marked as "Kids" cannot load videos carrying a maturity rating above PG.
• Video files have multiple stream tracks representing quality tiers (SD, HD, UHD/4K) and languages.
• A user's active stream must be routed to the closest geo-located Content Delivery Network (CDN) edge server that caches the target video file.

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