Usually, the workflow for getting an extension up and running involves a few steps. First, you need to find out which extension to use, which version, and the compatibility with your cluster. Once you have found out the extension you need, you have to install it in the cluster.
Installing it in the cluster really means deploying it in the cluster, that is, moving all the extension-related files and libraries into the shared directory of the cluster so that PostgreSQL can seek the code required to run the extension.
Lastly, you need to create the extension in every single database that needs it. Creating an extension is like enabling the usage of the extension within a specific database.
In order to demonstrate the usage of an extension, we will install Orafce, the Oracle compatibility functions extension. Describing the whole extension is not the aim of this section, so let's just say that this extension provides a set of functions, data types, and other stuff...