<type>text</type>
      </para>
      <para>
       Name of default version, or <literal>NULL</literal> if none is
       specified
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>installed_version</structfield> <type>text</type>
      </para>
      <para>
       Currently installed version of the extension,
       or <literal>NULL</literal> if not installed
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>comment</structfield> <type>text</type>
      </para>
      <para>
       Comment string from the extension's control file
      </para></entry>
     </row>
    </tbody>
   </tgroup>
  </table>

  <para>
   The <structname>pg_available_extensions</structname> view is read-only.
  </para>
 </sect1>

 <sect1 id="view-pg-available-extension-versions">
  <title><structname>pg_available_extension_versions</structname></title>

  <indexterm zone="view-pg-available-extension-versions">
   <primary>pg_available_extension_versions</primary>
  </indexterm>

  <para>
   The <structname>pg_available_extension_versions</structname> view lists the
   specific extension versions that are available for installation.
   See also the <link
   linkend="catalog-pg-extension"><structname>pg_extension</structname></link>
   catalog, which shows the extensions currently installed.
  </para>

  <table>
   <title><structname>pg_available_extension_versions</structname> Columns</title>
   <tgroup cols="1">
    <thead>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       Column Type
      </para>
      <para>
       Description
      </para></entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>name</structfield> <type>name</type>
      </para>
      <para>
       Extension name
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>version</structfield> <type>text</type>
      </para>
      <para>
       Version name
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>installed</structfield> <type>bool</type>
      </para>
      <para>
       True if this version of this extension is currently
       installed
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>superuser</structfield> <type>bool</type>
      </para>
      <para>
       True if only superusers are allowed to install this extension
       (but see <structfield>trusted</structfield>)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>trusted</structfield> <type>bool</type>
      </para>
      <para>
       True if the extension can be installed by non-superusers
       with appropriate privileges
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>relocatable</structfield> <type>bool</type>
      </para>
      <para>
       True if extension can be relocated to another schema
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>schema</structfield> <type>name</type>
      </para>
      <para>
       Name of the schema that the extension must be installed into,
       or <literal>NULL</literal> if partially or fully relocatable
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>requires</structfield> <type>name[]</type>
      </para>
      <para>
       Names of prerequisite extensions,