The Netflix Tech Blog: Netflix's Viewing Data: How We Know Where You Are in House of Cards

The Netflix Tech Blog: Netflix's Viewing Data: How We Know Where You Are in House of Cards

Netflix's Viewing Data: How We Know Where You Are in House of Cards

Over the past 7 years, Netflix streaming has expanded from thousands of members watching occasionally to millions of members watching over two billion hours every month.  Each time a member starts to watch a movie or TV episode, a "view" is created in our data systems and a collection of events describing that view is gathered.  Given that viewing is what members spend most of their time doing on Netflix, having a robust and scalable architecture to manage and process this data is critical to the success of our business.  In this post we'll describe what works and what breaks in an architecture that processes billions of viewing-related events per day.

Use Cases

By focusing on the minimum viable set of use cases, rather than building a generic all-encompassing solution, we have been able to build a simple architecture that scales.  Netflix's viewing data architecture is designed for a variety of use cases, ranging from user experiences to data analytics.  The following are three key use cases, all of which affect the user experience:

What titles have I watched?

Our system needs to know each member's entire viewing history for as long as they are subscribed.  This data feeds the recommendation algorithms so that a member can find a title for whatever mood they're in.  It also feeds the "recent titles you've watched" row in the UI.  What gets watched provides key metrics for the business to measure member engagement and make informed product and content decisions.

Where did I leave off in a given title?

For each movie or TV episode that a member views, Netflix records how much was watched and where the viewer left off.   This enables members to continue watching any movie or TV show on the same or another device.

What else is being watched on my account right now?

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