PostgreSQL

PostgreSQL originated as the POSTGRES project at UC Berkeley in 1986, led by Michael Stonebraker. SQL support was added in 1994, and the project was renamed PostgreSQL in 1996 when it became fully open-source. Nearly four decades later, it is the most widely deployed open-source relational database, known for correctness, standards compliance, and an exceptionally thorough documentation.

The database is fully ACID-compliant and ships with MVCC-based concurrency, write-ahead logging, and point-in-time recovery. Beyond standard SQL, it supports JSONB columns for semi-structured data, full-text search, range types, and GIS capabilities through the PostGIS extension. Custom types, functions, and extensions can be added without forking the core — a design that has produced a large ecosystem including pgvector for vector similarity search and TimescaleDB for time-series data.

Major releases follow an annual cycle with five years of support each. PostgreSQL 18 is the current major version. The PostgreSQL wiki and the mailing lists are the most authoritative sources for advanced configuration and internals.