Understanding how extensions work

Before digging into the extensions that are available, it is a good idea to take a look at how extensions work in the first place. Understanding the inner workings of the extension machinery can be quite beneficial.

Let's take a look at the syntax first:

test=# \h CREATE EXTENSION 
Command:     CREATE EXTENSION
Description: install an extension
Syntax:
CREATE EXTENSION [ IF NOT EXISTS ] extension_name
    [ WITH ] [ SCHEMA schema_name ]
             [ VERSION version ]
             [ FROM old_version ]
             [ CASCADE ]
URL: https://www.postgresql.org/docs/12/sql-createextension.html

When you want to deploy an extension, simply call the CREATE EXTENSION command. It will check for the extension and load it into your database. Note that the extension will be loaded into a database and not into the entire database instance.

If we are loading an...