title: Does it improve performance to index a date column?
body: <p>I have a table with millions of rows where one of the columns is a TIMESTAMP and against which I frequently select for date ranges.  Would it improve performance any to index that column, or would that not furnish any notable improvement? </p>
  
  <p>EDIT:</p>
  
  <p>So, I've indexed the TIMESTAMP column.  The following query
  <code>select count(*) from interactions where date(interaction_time) between date('2013-10-10') and date(now())</code></p>
  
  <p>Takes 3.1 seconds. </p>
  
  <p>There are just over 3 million records in the interactions table.</p>
  
  <p>The above query produces a result of ~976k</p>
  
  <p>Does this seem like a reasonable amount of time to perform this task?</p>