title: How to find implicitly generated indexes on postgresql
body: <p>Is there any way to detect if an index was generated automatically by the DBMS when adding, 
  e.g. the primary key or a unique constraint?</p>
  
  <p>At the moment I try to fetch all the indexes of an table by using jdbc metadata. But the result here contains also the implizit generated indexes. I need now the possibility to detect if a dedicated index was auto-generated or not. </p>
  
  <p>I've already tried to get these information from tables like pg_class or pg_index. But no success.</p>