Building Netflix’s Impression System: Powering Personalized Content Discovery at Scale

Introduction to Netflix Impressions

At Netflix, every image interaction during browsing is transformed into valuable data points called ‘impressions.’ These impressions are fundamental to creating personalized viewing experiences for millions of users worldwide, processing billions of interactions daily.

The Importance of Impression History

Impression history serves multiple critical functions in the Netflix ecosystem:

  • Enhanced Personalization: Tracks user content exposure to deliver fresh recommendations
  • Frequency Capping: Prevents content over-exposure and maintains engagement
  • New Release Management: Monitors initial user interactions for optimal content promotion
  • Analytics Support: Provides insights for platform performance and merchandising strategies

Technical Architecture

The system’s foundation is built on a robust Source-of-Truth (SOT) dataset, utilizing various modern technologies:

  • Apache Kafka for real-time event processing
  • Apache Iceberg for long-term data storage
  • Apache Flink for stream processing
  • Avro schema for data structuring

System Configuration and Scale

The infrastructure handles an impressive 1-1.5 million events per second globally. Each Flink deployment includes:

  • 8 task managers per region
  • 8 CPU cores and 32GB memory per manager
  • Parallelism of 48
  • Regional isolation using the ‘island model’

Quality Assurance and Future Development

Quality control is maintained through comprehensive column-level metrics and a tiered alerting system. Future improvements focus on:

  • Enhanced schema management for unschematized events
  • Automated performance tuning with autoscalers
  • Advanced data quality monitoring and alerting systems

This sophisticated system represents Netflix’s commitment to delivering personalized content discovery at scale, ensuring every user interaction contributes to a better viewing experience.

For more detailed information about Netflix’s Impression System, visit the Netflix Tech Blog