Complex sentence: EnterpriseDB develops and supports EnterpriseDB Advanced Server, an enterprise-class relational database management system (RDBMS) that is built on PostgreSQL, the world's most advanced open source database.
Split into simpler sentences: EnterpriseDB develops and supports EnterpriseDB Advanced Server, an enterprise-class relational database management system (RDBMS) that is built on PostgreSQL, one of the world's most advanced open source databases. EnterpriseDB is based on PostgreSQL, the world's most advanced open source database.