Ronald Bradford’s recent warning to be sure to know your my.cnf sections reminded me of a similar issue that I ran into last summer, where putting the “group” option in both the [mysqld_safe] and [mysqld] directives resulted in a mostly silent problem.

I started noticing this in MySQL 5.1 and it affected both the official MySQL binary and the Percona binary. In trying to be conscientious, I had the following set:

[mysqld_safe]
user=mysql
group=mysql

[mysqld]
user=mysql
group=mysql


However, when the MySQL server started up, the error log showed

[Warning] option 'group_concat_max_len': unsigned value 0 adjusted to 4

This was obviously a problem, but …

Yes, Maatkit’s name was inspired by Ma’at, which has an apostrophe. But there is NO apostrophe in the name of the popular toolkit for MySQL users.

I’m just sayin’.

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3. Making Maatkit more Open Source one step at a time If you

Related posts brought to you by Yet Another Related Posts Plugin.

I met Scott McNealy several times over the last year in customer meetings and to talk about Sun's open source strategy.  He's a class act all the way.  He sent out his final email to Sun employees and partners earlier today. 

Here's an excerpt:    

    While it was never the primary vision to be acquired by Oracle, it was always an interesting option. And this huge event is upon us now. Let’s all embrace it with all of the enthusiasm and class and talent that we have to offer.

    This combination has the potential to put Sun, its people, and its technology at the center of yet another industry and game changing inflection point. The opportunity is well documented and articulated by Larry and the …

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 O’Reilly MySQL Conference & Expo 2010 will be closing the Call for Participation at the end of the 27th January 2010. You have less than 48-hours – so get submitting already.

Take a gander at some of the shortlisted presentations, look at all the amazing tutorials, and what’s keeping you waiting from registering?

Related posts:

1. MySQL Conference Update: …

This Thursday (January 28, 17:00 UTC), we'll be resuming our MySQL University sessions with an Introduction to the Drizzle Microkernel by Brian Aker. Brian is located on the US West coast, so the session will start a bit later – see the information in the list of upcoming sessions. Brian started the Drizzle project and is the mastermind behind Drizzle development.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you …

Last week the Lucid Alpha3 development phase started. So in following our Alpha2 announcement below is what’s on the horizon for Alpha3. Some of these are new blueprints for Alpha3 some are continued work from Alpha2.

Alpha3 Projects

Since the upcoming release is an LTS, a lot of this cycles work is centered around stability. Currently, we’re broadly targeting the following 3 areas:

Software integration

• Eucalyptus 1.6.2
• Moving from MySQL 5.0 to 5.1
• …

MySQL Cluster Performance Tuning Best Practices

Are you experiencing current performance bottlenecks in your high availability applications ? Are you designing a new mission-critical application and want to know how best to structure your schema and index strategy for optimal performance? Interested in how to transform your SQL into faster, more efficient queries?

Benefits of connection pooling

Then this free web presentation is for you! You will get expert insight and learn best practices to help you identify those areas of database and application design that will give you the greatest benefits for performance when using MySQL Cluster.

We will discuss guidelines and best practices covering the following areas:

• General Design Concepts and Guidelines
• Schema …

Here’s a quick tip for using explain: You may know this already, but mysql will actually execute some subqueries when you invoke explain.  Here’s an example: mysql> explain select id from projects where id = (select max(id) from projects where name like 'en%'); +----+-------------+----------+-------+---------------+---------+---------+-------+-------+-------------+ | id | select_type | table | type | possible_keys | … Continue reading how to prevent explain from executing subqueries →

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1. Using the ENUM data type to increase performance While going through the DATA TYPES section of the Certification...

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