Databases & Data Storage
Cassandra
Definition
Apache Cassandra is a free and open-source, distributed, wide-column store, NoSQL database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure.
Why It Matters
Cassandra is designed for massive scale and extreme reliability. Its "masterless" architecture means that any node can handle any request, making it highly resilient to failure. It is used by companies like Netflix and Apple to handle enormous datasets.
Contextual Example
A streaming music service uses Cassandra to store user activity data. Every song a user plays is written to the database. Cassandra can handle the massive write load from millions of users and scale horizontally as the service grows.
Common Misunderstandings
- Cassandra prioritizes availability and partition tolerance over consistency (it is an "AP" system in CAP theorem terms).
- It has its own query language called CQL (Cassandra Query Language), which is similar in syntax to SQL.