Apache Cassandra Database

Apache Cassandra is a free and open-source distributed NoSQL database designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. Originally developed at Facebook by Avinash Lakshman and Prashant Malik in 2008 for inbox search, Cassandra was open-sourced and became an Apache Top-Level Project in 2010. Used by Netflix, Instagram, Apple, Spotify, and eBay to manage petabytes of data. Key features: distributed architecture (masterless ring topology with peer-to-peer gossip protocol, no master or coordinator nodes, eliminating single points of failure). Linear scalability (add or remove nodes without downtime, with automatic data redistribution via consistent hashing and virtual nodes vnodes). Multi-datacenter replication (configurable replication factor per datacenter, supporting geographic distribution and disaster recovery with tunable consistency levels per query). Tunable consistency (per-query consistency levels including ONE, QUORUM, LOCAL_QUORUM, ALL, and EACH_QUORUM for balancing latency and data accuracy). CQL (Cassandra Query Language with SQL-like syntax for creating tables, inserting data, and querying, with secondary indexes and materialized views). Partitioning (wide-column data model with partition keys for data distribution and clustering keys for ordering within partitions). Compaction strategies (Size-Tiered Compaction STCS, Leveled Compaction LCS, Time Window Compaction TWCS, and Incremental Compaction ICS for managing SSTable files). Compression (LZ4, Snappy, and Deflate compression for reducing storage and I/O overhead). Lightweight transactions (Paxos-based compare-and-set operations with linearizable consistency for conditional updates). CDC (Change Data Capture for tracking data modifications). Tools including nodetool for administration, sstableutil for file management, and Spark Cassandra Connector for analytics.