Cassandra: A Decentralized Structured Storage System

Cassandra is a decentralized, structured storage system initially developed by Facebook for its Inbox Search feature and later open-sourced. The document outlines Cassandra's architecture, including its data model (tables with column families), partitioning via consistent hashing, and replication strategies for high availability. It details the system's implementation, covering persistence components like Commit Logs and SSTables, the write and read paths, and the Staged Event-Driven Architecture (SEDA). The text also touches on Cassandra's motivations, its relationship to the CAP theorem and other NoSQL systems like Bigtable and Dynamo, and its evolution with the introduction of CQL and virtual nodes. Finally, it briefly discusses the Facebook Inbox Search schema and highlights Cassandra's strengths in write throughput and scalability, alongside considerations regarding security and its theoretical foundation.