PostgreSQL

PostgreSQL is a free and open-source relational database management system known for its extensibility, standards compliance, and robustness. It originated as POSTGRES, a research project at the University of California, Berkeley, and was later renamed PostgreSQL to reflect its support for SQL. It supports ACID-compliant transactions, multi-version concurrency control, and a rich set of data types and operators.

Architecturally, PostgreSQL relies on a write-ahead log and multi-version concurrency control to provide durability and concurrent access. It supports a wide range of procedural languages (such as PL/pgSQL, PL/Python, and PL/Perl) and an extensive ecosystem of extensions that can add data types, functions, and index types. Native features include JSON/JSONB data, hstore, full-text search, and robust indexing options (B-tree, GiST, SP-GiST, GIN, BRIN).

Replication and high availability options include streaming replication, logical replication, and hot standby. The platform also offers partitioning, parallel query execution, and optional just-in-time compilation to improve performance on large workloads. Security features include SSL support, authentication methods, and row-level security.

PostgreSQL is cross-platform and widely used in production for OLTP workloads, analytics, and data warehousing. It benefits from a large ecosystem of tools and drivers, with PostGIS providing advanced geospatial capabilities. The project is governed by the PostgreSQL Global Development Group and released under the permissive PostgreSQL License, a liberal open-source license.

Overall, PostgreSQL is recognized for reliability, feature richness, and extensibility, making it a common choice for organizations seeking a capable, standards-compliant database with a strong history of community and vendor support.