title: MySQL speed optimization on a table with many rows : what is the best way to handle it?
body: <p>I'm developping a chat application. I want to keep everything logged into a table (i.e. "who said what and when").
  I hope that in a near future I'll have thousands of rows.
  I was wondering : what is the best way to optimize the table, knowing that I'll do often rows insertion and sometimes group reading (i.e. showing an entire conversation from a user (look when he/she logged in/started to chat then look when he/she quit then show the entire conversation)).</p>
  
  <p>This table should be able to handle (I hope though !) many many rows. (15000 / day => 4,5 M each month => 54 M of rows at the end of the year).</p>
  
  <p>The conversations older than 15 days could be historized (but I don't know how I should do to do it right).</p>
  
  <p>Any idea ?</p>