Re: Dirt Slow Query On Datetime Range...the saga continues

Gabriel Ricard Wed, 12 Nov 2003 09:06:06 -0800

In order to make sure of a multi-column index, you have to order the WHERE clauses in the same order as the columns in the index. Since you query Realm first, then AcctStartTime, then AcctStopTime, MySQL would use an index on those columns in that order. You can either add a differently ordered index of the same columns or not, just make sure your query has the columns in the right order.

- Gabriel

On Tuesday, November 11, 2003, at 05:57 PM, Michael Shuler wrote:

Thanks for the quick help everyone...OK I made a few changes....

The Query is now: SELECT COUNT( * ) AS CallCount FROM ServiceRADIUSAccounting WHERE (Realm = 'testrealm.com') AND ('2003-10-11 16:00:00' BETWEEN AcctStartTime AND AcctStopTime) Which uses the RealmAndStart index (which as you see in the next line has been improved slightly).
And I modified the last key to:
KEY `RealmAndStart` (`Realm`,`AcctStartTime`,`AcctStopTime`)
I also though about it for a while and had an inspirational idea that if I make a key that looks like this: KEY `StartStopRealm` (`AcctStartTime`,`AcctStopTime`,`Realm`)

It would go even faster because it will narrow down to the records within the time frame (which is about 1000 records) and then down by the realm name which would result in ~150 records to count. Oddly enough in the EXPLAIN it doesn't even consider it as a possible index to use. What gets even more odd is that I swapped the BETWEEN and the Realm in the WHERE clause and then it decided to use just the plain Realm index...

SELECT COUNT( * ) AS CallCount FROM ServiceRADIUSAccounting WHERE ('2003-10-11 16:00:00' BETWEEN AcctStartTime AND AcctStopTime) AND (Realm = 'testrealm.com')

Is this a bug and is there a way to force MySQL to use an index that you know is a better choice?
Thanks again,
Michael Shuler
-----Original Message-----
From: Michael Shuler [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 11, 2003 3:44 PM
To: [EMAIL PROTECTED]
Subject: Dirt Slow Query On Datetime Range
OK, I give up. To anyone out there who can help me, please explain why this query runs slower than dirt. The table has about 1,300,000 records in it, which is not supposed to be a big deal for MySQL to deal with. I have tried it with MyISAM and then changed it to InnoDB which made it even slower but at least the rest of my queries can continue and not be blocked. This query takes 30 seconds on a dual 1GHz 1GB RAM RedHat 9 PC. In my opinion it should be 10x faster than that at the very least.

This table is used for RADIUS accounting, all I want to do is find the peak utilization port utilization for the day. The only way I have figured out how to do this is take samples every 5 min and store the highest one. Here is the table:
CREATE TABLE `ServiceRADIUSAccounting` (
  `RadAcctId` bigint(21) NOT NULL auto_increment,
  `AcctSessionId` varchar(32) NOT NULL default '',
  `AcctUniqueId` varchar(32) NOT NULL default '',
  `UserName` varchar(64) NOT NULL default '',
  `Realm` varchar(64) default '',
  `NASIPAddress` varchar(15) NOT NULL default '',
  `NASPortId` int(12) default NULL,
  `NASPortType` varchar(32) default NULL,
  `AcctStartTime` datetime NOT NULL default '0000-00-00 00:00:00',
  `AcctStopTime` datetime NOT NULL default '0000-00-00 00:00:00',
  `AcctSessionTime` int(12) default NULL,
  `AcctAuthentic` varchar(32) default NULL,
  `ConnectInfo_start` varchar(32) default NULL,
  `ConnectInfo_stop` varchar(32) default NULL,
  `XmitSpeed` varchar(6) default NULL,
  `RecvSpeed` varchar(6) default NULL,
  `AcctInputOctets` int(12) default NULL,
  `AcctOutputOctets` int(12) default NULL,
  `CalledStationId` varchar(11) NOT NULL default '',
  `CallingStationId` varchar(11) NOT NULL default '',
  `AcctTerminateCause` varchar(32) NOT NULL default '',
  `ServiceType` varchar(32) default NULL,
  `FramedProtocol` varchar(32) default NULL,
  `FramedIPAddress` varchar(15) NOT NULL default '',
  `AcctStartDelay` int(12) default NULL,
  `AcctStopDelay` int(12) default NULL,
  PRIMARY KEY  (`RadAcctId`),
  KEY `UserName` (`UserName`),
  KEY `FramedIPAddress` (`FramedIPAddress`),
  KEY `AcctSessionId` (`AcctSessionId`),
  KEY `AcctUniqueId` (`AcctUniqueId`),
  KEY `AcctStartTime` (`AcctStartTime`),
  KEY `AcctStopTime` (`AcctStopTime`),
  KEY `NASIPAddress` (`NASIPAddress`),
  KEY `Realm` (`Realm`),
  KEY `RealmAndStart` (`Realm`,`AcctStartTime`)
) TYPE=InnoDB AUTO_INCREMENT=4468368 ;
And here is the query:

SELECT COUNT(*) AS CallCount FROM ServiceRADIUSAccounting WHERE (Realm = 'testreal.com') AND (AcctStartTime <= '2003-11-11 15:30:00' AND AcctStopTime
= '2003-11-11 15:30:00')
When I do an explain I get: table type possible_keys key key_len ref rows Extra ServiceRADIUSAccounting ref AcctStartTime,AcctStopTime,Realm,RealmAndStart RealmAndStart 65 const 73394 Using where

Perhapse my InnoDB file needs to be "optimized" if such a thing exists. I don't know why this takes so long but I can definitly use some help. Thanks!

----------------------------------------

Michael Shuler
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Re: Dirt Slow Query On Datetime Range...the saga continues

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