pg_available_extensions
   The pg_available_extensions view lists the
   extensions that are available for installation.
   See also the
   pg_extension
   catalog, which shows the extensions currently installed.
  
Table 51.67. pg_available_extensions Columns
| Name | Type | Description | 
|---|---|---|
name | name | Extension name | 
default_version | text | Name of default version, or NULL if none is
       specified | 
installed_version | text | Currently installed version of the extension,
       or NULL if not installed | 
comment | text | Comment string from the extension's control file | 
   The pg_available_extensions view is read only.