The timing is consistent both ways - have tried both queries back-to-back alternatively many times. I'm pretty sure that it is not caching that causes the discrepancy. So, this turns out to be a known issue after all... Somehow I missed it. Thanks, Donny! Vadim. ----- Original Message ----- From: Donny Simonton To: 'Vadim P.' ; [EMAIL PROTECTED] Sent: Monday, March 29, 2004 9:34 PM Subject: RE: "ORDER DESC" vs. "ORDER ASC" exec time
Personally, it's an unexpected flaw that I hope one day will be fixed. But I'm not holding my breath, even though they seem to be planning for it. But it could also be because of query-cache. To benchmark something like this, you really need to add SQL_NO_CACHE to your select statement to get accurate numbers. Donny > -----Original Message----- > From: Vadim P. [mailto:[EMAIL PROTECTED] > Sent: Monday, March 29, 2004 8:16 PM > To: [EMAIL PROTECTED] > Subject: "ORDER DESC" vs. "ORDER ASC" exec time > > Hi all, > > Just noticed that a simple query that returns only 14 rows is 10X slower > when "ORDER .. DESC" is used compared to "ORDER .. ASC". > The table has about 700,000 records, indexed on the field the table is > being ordered by. > > Is this expected behavior? > > MySQL 4.0.18 running under OpenBSD 3.4 Intel/PIII 900MHz/2GB RAM > > ================================= > > mysql> SELECT distinct billingCycle FROM PhoneCalls ORDER BY > billingCycle DESC; > +--------------+ > | billingCycle | > +--------------+ > | 2004-04-01 | > | 2004-03-01 | > | 2004-02-01 | > | 2004-01-01 | > | 2003-12-01 | > | 2003-11-01 | > | 2003-10-01 | > | 2003-09-01 | > | 2003-08-01 | > | 2003-07-01 | > | 2003-06-01 | > | 2003-05-01 | > | 2003-04-01 | > | 2003-01-01 | > +--------------+ > 14 rows in set (14.77 sec) > > mysql> SELECT distinct billingCycle FROM PhoneCalls ORDER BY billingCycle; > +--------------+ > | billingCycle | > +--------------+ > | 2003-01-01 | > | 2003-04-01 | > | 2003-05-01 | > | 2003-06-01 | > | 2003-07-01 | > | 2003-08-01 | > | 2003-09-01 | > | 2003-10-01 | > | 2003-11-01 | > | 2003-12-01 | > | 2004-01-01 | > | 2004-02-01 | > | 2004-03-01 | > | 2004-04-01 | > +--------------+ > 14 rows in set (1.06 sec) > > mysql> > > > > > > > > > > > mysql > query > database > > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] >
