      delays do not occur during such operations.  Therefore it is
       possible that the cost accumulates far higher than the specified
       limit.  To avoid uselessly long delays in such cases, the actual
       delay is calculated as <code class="varname">vacuum_cost_delay</code> *
       <code class="varname">accumulated_balance</code> /
       <code class="varname">vacuum_cost_limit</code> with a maximum of
       <code class="varname">vacuum_cost_delay</code> * 4.
      </p></div></div><div class=