The latest from the MySQL community

If you have multiple database servers with strange names, or if you have to hop over multiple machines to connect to any mysql database server, then you know what a pain it can be to administer such a setup. Thanks to some scripting, you can automate such tasks as follows:

Create an expect script:
/path/to/sshmysql.exp

#!/usr/bin/expect -f
#script by darren cassar
#mysqlpreacher.com

set machine [lindex $argv 0]

set timeout -1

spawn ssh username@$machine
match_max 100000
expect -exact “assword: “
send — “password\r”
send — “sudo -k; sudo su – mysql\r”
expect -exact “sudo -k; sudo su – mysql”
expect -exact “assword:”
send — “password\r”
interact

# you should change the word password in ‘send — “password\r”‘ to your login password
# if you have the same password for each …

Following the opening keynote “Dolphins, now and beyond”, Marc Delisle presented on “State of phpMyAdmin”.

phpMyAdmin is an DBA administration tool for MySQL available today in 57 different languages. This is found today in many distributions, LAMP stack products and also in cpanel. The product is found at http://phpmyadmin.net.

There are current two versions, the legacy 2.x version to support older php 3.x & 4.x, The current version 3.x is for PHP 5.2 or greater.

The current UI includes some new features including.

• calendar input for date fields
• meta data for mime types e.g images, which is great for showing the output as an image, otherwise blob data
• Relational designer with the able to show and create foreign keys …

I had the honor of opening the day at the MySQL developer room at FOSDEM 2010 where I had a chance to talk about the MySQL product and community, now and what’s happening moving forward.

For those that missed the talk, my slides are available online at Slideshare however slides never due justice to some of the jokes including:

• What do you consider? the Blue Pill, or the Red Pill
• Why think two dimensionally, how about the Green Pill
• Emerging Breeds with performance enhancing modifications

Dolphins Now And Beyond – FOSDEM 2010 View more presentations from …

Those of you that know the documentation well will be aware of the old page we used to have for the MySQL documentation. It was huge, and over the years we’d done a number of things to try and improve the layout and make it easier to find what you wanted. We had in-age links to jump to the different documentation types, and the old topic table that allowed you to jump to specific parts of the documentation. The problem was that the more documentation that we produced (and there are over a thousand docs in various formats now), the bigger the page got. When we added the individual topic guides, for example, we trebled the size of the page by adding the links for each individual topic guide. Ultimately that makes it increasingly difficult for you guys to find what you are looking for, despite the quick links and other elements. We’ve now changed all this and split the single, big, monolithic …

Those of you that know the documentation well will be aware of the old page we used to have for the MySQL documentation. It was huge, and over the years we’d done a number of things to try and improve the layout and make it easier to find what you wanted. We had in-age links to jump to the different documentation types, and the old topic table that allowed you to jump to specific parts of the documentation.

The problem was that the more documentation that we produced (and there are over a thousand docs in various formats now), the bigger the page got. When we added the individual topic guides, for example, we trebled the size of the page by adding the links for each individual topic guide.

Ultimately that makes it increasingly difficult for you guys to find what you are looking for, despite the quick links and other elements.

We’ve now changed all this and split …

I have been upgrading more MySQL database instances recently and have found a few more potential gotchas, which if you are not careful, can potentially be rather nasty. These are not documented explicitly by MySQL, so it may be handy for you to know if you have not come across this type of thing before.

Most of the issues are those related to upgrading MySQL instances which are replicated, either the master servers or the slaves. Some seem specific to the rpm packages I am using (MySQL enterprise or MySQL advanced rpms), though others are not.

Take care upgrading a 5.0 master when you have 5.1 slaves

It is not a good idea to run a mixed major version of mysql in a replicated environment so why would I be doing this? If you work in a replicated environment and have several slaves then it is recommended that you upgrade the slaves first. I work with quite a few slaves so the process of upgrading them all takes longer …

The MySQL configuration file, e.g. /etc/my.cnf has a number of different section headings including [mysql], [mysqld], [mysqld_safe]. It is important that you ensure you put the right variables into the right section. For example, the following my.cnf configuration file will not operate as the user probably expects.

[mysqld]
...
log-bin=mysql-bin
server-id=1
query_cache_size = 100M
query_cache_type = 1

...

[mysqld_safe]
...
key_buffer_size=600M
skip-innodb
...

In this example, this configuration does not give you a MyISAM key buffer of 600M, it’s actually the default of 8M.

mysql> show global variables like 'key_buffer_size';
+-----------------+---------+
| Variable_name   | Value   |
+-----------------+---------+
| key_buffer_size | 8388600 |
+-----------------+---------+

Be sure to add the right options to the [mysqld] section.

What I didn’t know until yesterday was that some programs read from …

I hit this interesting problem last night on 5.0.51a.

mysql> use information_schema;
mysql> desc routines;
ERROR 1 (HY000): Can't create/write to file '/home/tmp/#sql_fea_1.MYD' (Errcode: 24)
mysql> show create table routines\G
*************************** 1. row ***************************
       Table: ROUTINES
Create Table: CREATE TEMPORARY TABLE `ROUTINES` (
  `SPECIFIC_NAME` varchar(64) NOT NULL default '',
  `ROUTINE_CATALOG` varchar(512) default NULL,
  `ROUTINE_SCHEMA` varchar(64) NOT NULL default '',
  `ROUTINE_NAME` varchar(64) NOT NULL default '',
  `ROUTINE_TYPE` varchar(9) NOT NULL default '',
  `DTD_IDENTIFIER` varchar(64) default NULL,
  `ROUTINE_BODY` varchar(8) NOT NULL default '',
  `ROUTINE_DEFINITION` longtext,
  `EXTERNAL_NAME` varchar(64) default NULL,
  `EXTERNAL_LANGUAGE` varchar(64) default NULL,
  `PARAMETER_STYLE` varchar(8) NOT NULL default '',
  `IS_DETERMINISTIC` varchar(3) NOT NULL default '',
  `SQL_DATA_ACCESS` varchar(64) NOT …

The Problem

I've had MySQL on my Windows 7 laptop for a bit (as part of wampserver), mostly for local offline WordPress development.

However, even though MySQL is relatively stable, I've been observing a vast quantity of intermittent MySQL errors, as reported by WordPress in the PHP error log (C:\wamp\logs\php_error.log). Here are some examples:

[05-Jan-2010 09:47:51] WordPress database error Error on delete of
'C:\Windows\TEMP\#sql17e0_1a2_6.MYD' (Errcode: 13) for query SELECT t.*, tt.* 
FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON tt.term_id = t.term_id 
INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = 
tt.term_taxonomy_id WHERE tt.taxonomy IN ('category') AND tr.object_id IN (3) 
ORDER BY t.name ASC made by require, require_once, include, get_footer, 
locate_template, load_template, require_once, dynamic_sidebar, 
call_user_func_array, …

Normally I like to use the OS’s package manager to manage the software on my system. This ensures that things are done consistently. When managing MySQL I’d also like to manage all my instances the same way. That makes life easier for me but also for my fellow DBAs and sysadmin colleagues.

I use CentOS and the rpm packages it provides and these work quite well. However, the MySQL rpms do not allow me to manage single and multiple instances alike and while mysqld runs as the mysql user the instance management needs to be done as root (stopping, starting instances, or default access). If you want to run multiple instances you can also use mysqld_multi, but that’s not the default setup.

So this is not ideal. While this may not be much of an issue if you manage a single server, if you manage tens or …