The programs needed to create and run a PostgreSQL server
PostgreSQL is an advanced Object-Relational database management system (DBMS). The postgresql-server package contains the programs needed to create and run a PostgreSQL server, which will in turn allow you to create and maintain PostgreSQL databases.
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Extension modules distributed with PostgreSQL
The postgresql-contrib package contains various extension modules that are included in the PostgreSQL distribution.
PostgreSQL development header files and libraries
The postgresql-server-devel package contains the header files and configuration needed to compile PostgreSQL server extension.
The test suite distributed with PostgreSQL
The postgresql-test package contains files needed for various tests for the PostgreSQL database management system, including regression tests and benchmarks.