How to fix Required extension is not installed in PostgreSQL

Connect to PostgreSQL and query the pg_available_extensions view to see which extensions the server can load:

SELECT * FROM pg_available_extensions WHERE name LIKE '%extension_name%';

If your extension is not listed, it means the extension files are not installed on the system.

For Debian/Ubuntu systems, install the postgresql-contrib package which contains common extensions:

sudo apt-get update
sudo apt-get install postgresql-contrib

For other distributions:
- RedHat/CentOS/Fedora: sudo yum install postgresql-contrib
- Alpine: apk add postgresql-client
- macOS with Homebrew: brew install postgresql

After installation, restart PostgreSQL to ensure the new extensions are recognized.

Once the extension files are available on the system, you can load the extension into a specific database. Connect as a superuser and run:

CREATE EXTENSION IF NOT EXISTS extension_name;

The IF NOT EXISTS clause prevents errors if the extension is already loaded. To load the extension into a specific schema:

CREATE EXTENSION IF NOT EXISTS extension_name SCHEMA extensions_schema;

Some extensions depend on other extensions being installed first. If you see a dependency error, use the CASCADE keyword to automatically install required dependencies:

CREATE EXTENSION IF NOT EXISTS extension_name CASCADE;

You can check extension dependencies by querying:

SELECT name, requires FROM pg_available_extensions WHERE name = 'extension_name';

After creating the extension, verify it's properly installed in your database:

SELECT * FROM pg_extension WHERE extname = 'extension_name';

You can also list all extensions in the current database:

\dx

The extension should now be available for use.