Postgres Pro is designed to be easily extensible. For this reason, extensions loaded into the database can function just like features that are built in. The extensions shipped with Postgres Pro are described in Appendix F. Other extensions are developed independently, like PostGIS. Even Postgres Pro replication solutions can be developed externally. For example, Slony-I is a popular primary/standby replication solution that is developed independently from the core project. Some extensions are made compatible with Postgres Pro Enterprise, for example, citus. Consult the Postgres Pro Enterprise support team if you want to gain access to such extensions.