 table have been vacuumed away.
         Some tables cannot safely be vacuumed early, and so will not be
         affected by this setting, such as system catalogs.  For such tables
         this setting will neither reduce bloat nor create a possibility
         of a <span class="quote">“<span class="quote">snapshot too old</span>”</span> error on scanning.
        </p></dd></dl></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="lef