 the
  database user name that was requested.
 </p><p>
  <span class="productname">PostgreSQL</span> offers a number of different
  client authentication methods. The method used to authenticate a
  particular client connection can be selected on the basis of
  (client) host address, database, and user.
 </p><p>
  <span class="productname">PostgreSQL</span> database user names are logically
  separate from user names of the operating system in which the server
  runs. If all the users of a particular server