How to gain performance through MySQL

[Colin Guthrie]

Rich wrote:
> Andreas Baier wrote:
>> Hello,
>>
>>> what is the exact mysql version ? have you changed that lately ?
>>> can you upgrade to the latest mysql ?
>> Unfortunately I'm not at home today, but as far as I know, it has to be the 
>> latest release in portage: mysql-5.0.32.
> 
> in your initial mail, i noticed :
> 
> # /etc/mysql/my.cnf: The global mysql configuration file.
> # $Header: /var/cvsroot/gentoo-x86/dev-db/mysql/files/my.cnf-4.1,v 1.3
> 
> but that's probably some internal cvs version or something, right ?
> 
> could it be that you have updated mysql from 4.x at some point recently ?
> 
> you could try looking at the db (especially statistics table), and see 
> what type does 'url' has.
> if it is "varchar", try to change it to varbinary(255) and see whether 
> that helps a bit.
> 
> of course, doublecheck that you have a good backup before changing the db ;)
> ...

If there was a file system upgrade of Mysql 4 to 5 then it can have some
odd effects with varbinary fields. They will be padded to the full
lenght of the field.

This does not happen if you dump the DB under mysql 4 then reimport
after upgrading.

I've just done a server migration for various website with regard to
mysql 4 to 5 upgrade and it strongly recommends against the disk based
upgrade....

This could be the problem if there are varbinary fields in mysql database.

Read the notes on the Mysql site about this and the various tricks to
fixing it after the event....

All the best.

Col