 class="type">integer</code>)
       <a id="id-1.6.7.7.5.5.4.1.3" class="indexterm"></a>
       </span> <a href="#GUC-VACUUM-COST-PAGE-DIRTY" class="id_link">#</a></dt><dd><p>
         The estimated cost charged when vacuum modifies a block that was
         previously clean. It represents the extra I/O required to
         flush the dirty block out to disk again. The default value is
         20.
        </p></dd><dt id="GUC-VACUUM-COST-LIMIT"><span class="term"><code class="varname">vacuum_cost_limit</cod