pg_available_extension_versions view lists the
specific extension versions that are available for installation.
See also the
catalog, which shows the extensions currently installed.
|True if this version of this extension is currently installed|
|True if only superusers are allowed to install this extension|
|True if extension can be relocated to another schema|
|Name of the schema that the extension must be installed into,
|Names of prerequisite extensions,
|Comment string from the extension's control file|
pg_available_extension_versions view is read