H.4. Extensions
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## H.4. Extensions #

PostgreSQL™ 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 PostgreSQL™ 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.

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