 all foreign tables using <code class="filename">postgres_fdw</code> are assumed
    to be updatable.  This may be overridden using the following option:
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">updatable</code> (<code class="type">boolean</code>)</span></dt><dd><p>
       This option controls whether <code class="filename">postgres_fdw</code> allows foreign
       tables to be modified using <code class="command">INSERT</code>, <code class="comm