Goal Try to use as much the possibilities of the DBMS as possible. On the other hand, do not install extensions that are not needed in order not to overcomplicate the database.
Type General (Overview of some aspect of the database.)
License MIT License
Fixing Suggestion If you do not need an extension, then drop it.
Data Source system catalog only
SQL Query
SELECT name, installed_version, comment
FROM pg_catalog.pg_available_extensions
WHERE installed_version IS NOT NULL
ORDER BY name;

SQL statements that help generate fixes for the identified problem.

SQL Query to Generate FixDescription
SELECT format('DROP EXTENSION %1$I;', name) AS statements
FROM pg_catalog.pg_available_extensions
WHERE installed_version IS NOT NULL
ORDER BY name;
Drop the extension.
Collections

This query belongs to the following collections:

NameDescription
Find problems by overviewQueries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not .
Categories

This query is classified under the following categories:

NameDescription
Comfortability of data managementQueries of this category provide information about the means that have been used to make the use or management of database more comfortable and thus, more efficient.
ExtensionsQueries of this category provide information about extensions in the database.
SecurityQueries of this category provide information about the security measures.

Further reading and related materials:

Reference
There are quite a lot of extensions that are shipped together with the PostgreSQL source code.
Anyone can create an extension and there are many examples: https://pgxn.org/