7 reasons why Netflix uses Cassandra Databases


Who doesn’t love a good Netflix binge? The opportunity to enjoy your favourite new show or any number of great movies appeals to many of us. In fact, it appeals to around 100 million subscribers worldwide.

There’s a good reason Netflix is doing so well, and it’s not just about content. The technology powering Netflix has been selected to deliver scale, availability, flexibility, performance and — ultimately — the best possible customer experience. In this article, we want to highlight one of those core database technology choices – Netflix’s decision to use the Apache Cassandra database.

It’s Extremely Scalable

Netflix is a very large production deployment of Cassandra, accounting for 2,500 nodes, 420 TB, and over one trillion requests per day. SQL databases are more relational, rigid and structured compared to NOSQL databases. Cassandra, being a NOSQL database is non-relational, distributed and document-oriented, allowing it to scale horizontally and dynamically as more servers are added without needing to re-shard or reboot.

It’s a Proven Solution

As a free and open-source NOSQL database management system, Cassandra has proven itself time and again as being able to provide high availability while handling very large amounts of data across servers. It’s favoured by more than 1,500 organisations including leaders like Netflix, eBay, Comcast, Instagram and Reddit.

It’s Strong on Performance

Cassandra is well regarded for consistently outperforming other NoSQL solutions in benchmarks, as well as in real-world applications. Netflix believe the performance is strong, especially for the write throughput, with the University of Toronto concluding after testing that “Cassandra achieves the highest throughput for the maximum number of nodes in all experiments with a linear increasing throughput from 1 to 12 nodes.”

It’s a Decentralised Database Technology

A big part of Apache Cassandra’s appeal is there are no single points of failure, and there are no network bottlenecks. The implications for a content and data-intensive business such as Netflix are immense. Decentralisation means there are no dedicated name nodes and no practical architectural limitations on data sizes or row/column counts.

It’s Big on Flexibility 

Cassandra’s data model is extremely flexible. Organisations like Netflix love the fact that the sparse two-dimensional “super-column family” architecture allows for rich data model representations (and better performance) beyond just a simple key-value look up.

It’s Great for Multiple Geographies

Growing businesses like Netflix find Cassandra’s geographic capabilities to be a big plus — a single global cluster can simultaneously replicate data asynchronously as well as service applications across multiple locations. Cassandra is a good choice for cross-datacentre and cross-regional deployments as customisable replication helps determine which cluster nodes to designate as replicas.

It’s Professionally Supported

Apache Cassandra is supported by a number of expert technical firms and managed services providers — which is a good choice for startups concentrating on growth. Being able to access high-level professional support via a managed Apache Cassandra service allows businesses like Netflix to focus on what they do best: delivering an exceptional service, innovating their offering, adding features to their product, building their brand in the marketplace and engaging with their customer base.