title: Large MySQL Table Update Slow
body: <p>Hi this is my table structure</p>
  
  <pre><code>CREATE TABLE IF NOT EXISTS `sms_report` (
   `R_id` int(11) NOT NULL auto_increment,
   `R_uid` int(11) NOT NULL,
   `R_smppid` varchar(100) collate utf8_unicode_ci NOT NULL,
   `R_from` varchar(10) collate utf8_unicode_ci NOT NULL,
   `R_status` longtext collate utf8_unicode_ci NOT NULL,
   `R_message` text collate utf8_unicode_ci NOT NULL,
   `R_numbers` longtext collate utf8_unicode_ci NOT NULL,
   `R_timestamp` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
   `R_timedate` varchar(40) collate utf8_unicode_ci NOT NULL,
   `R_show` int(11) NOT NULL default '1',
   `oldformat` tinyint(1) NOT NULL default '0',
   PRIMARY KEY  (`R_id`)
  </code></pre>
  
  <p>) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1947722 ;</p>
  
  <p>I have approx 2 million rows so when I do an update on R_status here, it seem to take too long(R_status is either 1,2,16 or 24).
  Please suggest on how to optimise.</p>