method configures operations performed
         using the specified <a class="link" href="env.html" title="Chapter 5.  The DB_ENV Handle">DB_ENV</a>  
         handle, not all operations performed on the underlying database environment.
    </p>
      <p>
         The <code class="methodname">DB_ENV-&gt;add_data_dir()</code> method may not be called after the 
         <a class="xref" href="envopen.html" title="DB_ENV-&gt;open()">DB_ENV-&gt;open()</a>  method is called.
         If the database environmen