built-in objects are visible
   without schema qualification.  This is not an issue for queries
   generated by <code class="filename">postgres_fdw</code> itself, because it always
   supplies such qualification.  However, this can pose a hazard for
   functions that are executed on the remote server via triggers or rules
   on remote tables.  For example, if a remote table is actually a view,
   any functions used in that view will be executed with the restricted
   search path.  It is recommended to schem