title: Oracle: find Block session in the past
body: <p>I had a problem with session of DB in the past.
  My problem is i have some session of DB blocked in the past 4 day.
  I want to trace why those session blocked to fixed it.
  I tried many way and searching in Google to a achieved this purpose not no hope.</p>
  
  <p>I looked up in table: </p>
  
  <blockquote>
    <p>V$ACTIVE_SESSION_HISTORY, dba_hist_active_sess_history,sys.WRH$_ACTIVE_SESSION_HISTORY</p>
  </blockquote>
  
  <p>But no clue.</p>
  
  <p>Please help me solve it.</p>
  
  <p>Thanks.</p>