[snip] > The way to > enhance this is by selecting an indexed value, such as the following > where `foo` is indexed > > SELECT `foo` FROM fortunes ORDER BY RAND() LIMIT 1
Why does this help? From the MySQL book I have, the reason ORDER BY RAND() is slow is because "for each record in the table a random number must be generated. Then all random numbers are sorted so that the first n records can be returned. Is this correct? If so, how does selecting an indexed column help this, won't it still need to perform all those operations (generate rand-nums, then sort) regardless of the index? [/snip] Using indexes for selection criteria does have an impact, even with RAND. On a table such as yours it shouldn't matter due to the small size. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
