Tantor SE is designed to be easily extensible. For this reason, extensions loaded into the database can function just like features that are built in. The contrib/ directory shipped with the source code contains several extensions, which are described in Appendix F. Other extensions are developed independently, like PostGIS. Even Tantor SE 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.