"Having recently upgraded my forum software," Kinta wrote, "I noticed that my site had been running incredibly slow."

"Upon further investigation, I found that that the following code was being run once for each and every comment on a page, whenever ever a forum thread was opened.

 

function ItemCache($bNewConnection = false)
{
   $this->sql = new SqlHelper(dbhost, dbname, dbuser, dbpass, $bNewConnection);
   $this->connected = $this->sql->connected;

   $query = "SELECT item_id FROM item_cache";
   $returnValue = $this->sql->query($query);
     
   if ($returnValue == false)
   {
      $query = "ALTER TABLE item_cache ADD `item_id` 
                VARCHAR(100) DEFAULT '0' AFTER `item_name`";
      $returnValue = $this->sql->query($query);
         
      $query = "ALTER TABLE item_cache ADD `item_lang`
                VARCHAR(2) DEFAULT '' AFTER `item_id`";
      $returnValue2 = $this->sql->query($query);
         
      if ($returnValue == false || $returnValue2 == false)
      {
        // Create the item cache table.
        $query = "CREATE TABLE IF NOT EXISTS `item_cache` (
                  ### snip ###
        $this->sql->query($query);
      }
   }
}

"It's fetching data from all rows from the entire item_cache table (currently several thousand), twenty-five times for every page load... just to check if the table exists and has the right columns.