Which database is an example of an open-source relational database management system?

• A. PostgreSQL
• B. Microsoft Access
• C. Oracle Database
• D. IBM Db2

Answer: (A)

Open-source relational database management systems are those whose source code is freely available to inspect, modify, and distribute under licenses that allow broad use. PostgreSQL fits this description perfectly. It’s developed by a global community and released under a permissive open-source license, making its code accessible to anyone. PostgreSQL implements SQL, is ACID-compliant, and offers robust features like advanced querying, transactional integrity, extensibility with custom data types and extensions, and cross-platform support.

In contrast, Microsoft Access is a proprietary desktop database, while Oracle Database and IBM Db2 are commercial, closed-source products. This combination makes PostgreSQL the clear example of an open-source relational database management system.