r: both">72.2. Implementation <a href="#HASH-IMPLEMENTATION" class="id_link">#</a></h2></div></div></div><p>
  There are four kinds of pages in a hash index: the meta page (page zero),
  which contains statically allocated control information; primary bucket
  pages; overflow pages; and bitmap pages, which keep track of overflow
  pages that have been freed and are available for re-use. For addressing
  purposes, bitmap pages are regarded as a subset of the overflow pages.
 </p><p>
  Both scanning the inde