gentoo-overlay/dev-db/pg-gvm/files/README.gentoo

To use the extension in a database create the extension using
CREATE EXTENSION "pg-gvm";

You can do this on the gvmd database running:

root ~ # sudo -u postgres psql gvmd
gvmd=>	CREATE EXTENSION "pg-gvm";
gvmd=>	\q

Please, read: https://github.com/greenbone/pg-gvm/#use-the-extension