On Wed, Jun 2, 2010 at 10:28 AM, Lin Chun <franks1...@gmail.com> wrote: > *don't know it very clear, but i think is the problem of <derived> seems it > take full scaning*
Yes, it has no indexes so it isn't good for very large subqueries. You should create them as temporary tables instead and give them indexes. - Perrin -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
