2006/4/14, Philippe Poelvoorde <[EMAIL PROTECTED]>: > Hi, > > I have one table : > CREATE TABLE `ressources_summary` ( > `res_type` tinyint(3) unsigned NOT NULL default '0', > `res_id` int(10) unsigned NOT NULL default '0', > `comment_count` smallint(5) unsigned NOT NULL default '0', > `comment_last_timestamp` timestamp NOT NULL default '0000-00-00 00:00:00', > `comment_last_user_id` int(11) NOT NULL default '0', > PRIMARY KEY (`res_type`,`res_id`) > ) ENGINE=MyISAM > > it gather summary on comments for any ressources (poll, articles, > forums, admin). A ressource is uniquely identify by (res_type, > res_id), the others columns are self-explanatory (I hope). > I'm wondering about the efficiency of storing a comment_count of 0 > (and user_id=0, timestamp=0). > There is comments on 20% of the ressources. > What is the cost of looking for a row that does not exists in a table ? > Would it be more efficient to only store summary for comment_count > greater than 0 and knowing missing rows have a count of zero, or to > store everything ?
I went for the version without all zeros. It dramatically reduce the number of rows, and overall performances are better with this summary table. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
