title: How to avoid full table scan query between dates
body: <p>I am writing a stored proc to insert summarized values into task_activity_report table from task_history table. </p>
  
  <p>Table</p>
  
  <pre><code>Task_history
  ----------------------------------------
  Task_id                    Varchar2(32) PK
  Event_dt                   Date
  Event                      Varchar2(10)
  ......
  ......
  ......
  </code></pre>
  
  <p>SQL Query:</p>
  
  <pre><code>SELECT task_id 
  FROM   task_history 
  WHERE  event = 'CLOSED' 
         AND event_dt BETWEEN 10 - nov - 13 AND 20 - nov - 13; 
  </code></pre>
  
  <p>Between dates is doing full table scan, how to avoid full table scan query between dates??
  select task_id from task_history where event_dt between 10-NOV-13 AND 20-NOV-13;</p>
  
  <p>My table has 15millions+ records </p>
  
  <p>Thanks for your help and time on this. Much appropriated.</p>
  
  <p>CVSR Sarma </p>