title: role "SYSTEM" does not exist in postgresql
body: <p>I created a function in dbname "migrate" to store values from another dbname called "Fulfil.1.9.1" 
  while executing function i'm getting error like this </p>
  
  <blockquote>
    <p>role "SYSTEM" does not exist</p>
  </blockquote>
  
  <pre><code>insert into ns_fw_theme(theme_id, theme_name)
  select theme_id,
         theme_name
  from dblink('dbname=Fulfil_1.9.1','select theme_id,
                                     theme_name from ns_fw_theme')
    AS t1(theme_id character varying(100), theme_name character varying(100));
  </code></pre>