Re: Question from a new user:MySQL vs MS SQLserver merges - Brent Baisley - com.mysql.lists.mysql

4 messages in com.mysql.lists.mysqlRe: Question from a new user:MySQL vs...

From	Sent On	Attachments
jatwood	28 Apr 2005 14:35
Alec...@Quantel.Com	29 Apr 2005 08:10
Brent Baisley	29 Apr 2005 10:05
mfat...@free.fr	29 Apr 2005 10:13

Subject:	Re: Question from a new user:MySQL vs MS SQLserver merges
From:	Brent Baisley (bre...@landover.com)
Date:	04/29/2005 10:05:12 AM
List:	com.mysql.lists.mysql

It sounds like you either have incorrect indexes or you didn't adjust the MySQL configuration variables (i.e. key_buffer, join_buffer_size, read_buffer_size) appropriately for your data set size and what your query is doing (i.e. full table scan).

SHOW STATUS can help you figure out what needs to be adjusted, like Key_reads vs. Key_read_requests ratio.

On Apr 28, 2005, at 5:35 PM, jatwood wrote:

I am new to MySQL. Please excuse my ignorance if this question has been previously discussed. I was not able to

find an answer to my question by searching the archives.

I have MySQL installed on a dedicated AMD-64 computer with the MS XP Pro operating system.

MS-SQLServer is installed on a 32-bit machine with a slower clock speed. I am running the free binary

distribution of MySQL for testing purposes and have been generally impressed with

MySQL's comparative performance in all but one area.

I am finding that both inner and outer merges take substantially longer with MySQL than with the SQLServer using the same basic code.

In one application a left outer merge between a file with 600,000 records and a file with 4,500,000 records took about 10-15 minutes with

SQLServer and 11 hours with MySQL. I am repeatedly having similar experiences with both inner and outer merges.

Is there any way I can try to improve MySQL's performance with respect to merges? Needless to say, unless I can improve MySQL's

performance, I will not be converting to MySQL at this time.

Thanks