literal">S_IRUSR</code> and <code class="literal">S_IWUSR</code>,
                    or octal mode 0600 on historic UNIX systems), some
                    filesystems may not sufficiently protect temporary files
                    created in random directories from improper access. To be
                    absolutely safe, applications storing sensitive data in
                    unnamed databases should use the 
                    
                    <code class="methodname">DbEnv::set_tmp_dir()</co