Hello,
On 11/02/2002 03:21 AM, Leif K-Brooks wrote:
> I've been optimizing scripts in an attempt to speed my friend's site up,
> and I believe I've found the source of the performance problems. When I
> comment the following page load time changes from around 6 seconds to
> less than .5 of a second.
>
> if($loggedin){
> $events = mysql_query("select * from events where
> whofor='{$userinfo['id']}' order by id desc limit 1");
> if(mysql_num_rows($events) == 1){
> $events = mysql_fetch_array($events);
> print <<< END
> <p align="center"><a
> href="{$basepath}doevent.php?id={$events['id']}">{$events['message']}</a></p>
>
> END;
> }
> }
>
> This code checks for events (new mail, etc.) that the user may have and
> dispays them. Any idea on what makes it perform this badly?
The order by clause is the killer. It forces the server to rebuild the
whole table in memory just to returned the results sorted. If you just
want the highest id, use MAX(id) .
--
Regards,
Manuel Lemos
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