</dl></dd></dl></div><a id="id-1.10.12.2" class="indexterm"></a><p>
  <span class="productname">PostgreSQL</span> supports a set of experimental facilities which
  are intended to allow extension modules to add new scan types to the system.
  Unlike a <a class="link" href="fdwhandler.html" title="Chapter 59. Writing a Foreign Data Wrapper">foreign data wrapper</a>, which is only
  responsible for knowing how to scan its own foreign tables, a custom scan
  provider can provide an alternative method of scan