php - order by rand() 给大帖子带来麻烦

Question

我有这段代码，这段代码遇到了麻烦，需要执行很多时间来显示来自数据库的随机帖子:

$totalrows = 10;

$sql = "SELECT 
 posts.Tags as tags, 
 posts.OwnerUserId as postsid, 
 posts.Id as postid, 
 posts.Body as body, 
 posts.Title as title, 
 users.Id as userid, 
 users.DisplayName as usersname  
FROM posts 
JOIN users ON posts.OwnerUserId = users.Id 
WHERE posts.Title != '' order by rand() asc limit " .  $totalrows;

$r = mysql_query($sql) or die(mysql_error());

请告诉我应该如何更改才能更快地显示随机帖子？

问候，丹

Answer 1

rand() 非常昂贵。这将有助于:http://www.titov.net/2005/09/21/do-not-use-order-by-rand-or-how-to-get-random-rows-from-table/