When you use SHOW STATUS can can restrict with the LIKE syntax, allowing for a subset of values. For example:

mysql> SHOW GLOBAL STATUS LIKE 'Com%';
+--------------------------+-------+
| Variable_name            | Value |
+--------------------------+-------+
| Com_admin_commands       | 0     |
| Com_alter_db             | 0     |
| Com_alter_table          | 0     |
| Com_analyze              | 0     |
| Com_backup_table         | 0     |
| Com_begin                | 0     |
| Com_change_db            | 0     |
| Com_change_master        | 0     |
...

That’s great, but sometimes you want specific values. Using WHERE can achieve this. For Example.

mysql> SHOW GLOBAL STATUS WHERE VARIABLE_NAME IN (?Com_insert?,'Innodb_buffer_pool_pages_latched?,'threads_running?);
+----------------------------------+-------+
| Variable_name                    | Value |
+----------------------------------+-------+
| Com_insert                       | …

Last night at the MySQL NY Meetup we continued on from a very successful July presentation on “Practical Performance Tips & Tricks”. I must admit after speaking and standing all day for the MySQL DBA Bootcamp for the Oracle DBA it was a stretch, and we didn’t cover all material as expected, but the evening was still very productive to everybody. Links are here for my August Presentation and July Presentation.

Thanks to Marc and the team from LogicWorks for again sponsoring our NY Meetup Event. We don’t get the beer and food any other way.

As a …

This week I presented two one day free seminars, “MySQL DBA Bootcamp for the Oracle DBA” in New York and San Francisco. Both were very successful days providing an opportunity to speak to seasoned enterprise professionals.

One question I was asked was “As an Oracle DBA, how can I become a MySQL DBA, what do I do, where do I start?”

Here are my references and recommendations that have zero cost to get started.

• Read the MySQL Documentation Reference Manual.
• Download MySQL install and use it.
• The MySQL Developer Zone is a great sources for articles, information and references.
• …

We have all done it in the past, and probably most people that read this (will admit| or lie) to still doing it, but everybody must start making an effort to improving MySQL security in the usage on your MySQL Installation, including just on your laptop, and in presentations that people read.

I spotted a reference article on Planet MySQL this evening and without looking at the details the syntax presented typifies two basic and fundamental 101 MySQL security issues.

1. Always, always, always have a password for a MySQL account, especially for the ‘root’ user.
2. Don’t use the ‘root’ user unless you really have to. The SUPER privilege is just that SUPER, there are many things you really don’t want every person accessing to have. In a larger environment …

While using the latest MySQL 5.1.20 yesterday I came across another situation that was not expected as with previous editions of MySQL. The background is experimenting with DRBD. When I configured MySQL to startup with a /etc/my.cnf file with data on a DRBD partition I got a failed startup error message with mysqld_safe.

$ bin/mysqld_safe &
[1] 12615
070720 10:10:42 mysqld_safe Starting mysqld daemon with databases from /drbd/data
070720 10:10:42 mysqld_safe mysqld from pid file /drbd/data/newyork.localdomain.pid ended

Ok. Well this happens so I went to the data directory to look for `hostname`.err.

$ cd /drbd/data
$ ls -l

What the! There is no error log. Then the discussion started about this. Apparently mysqld_safe now uses syslog (e.g. /var/log/messages) for logging messages. Ok, but where is the line between mysqld_safe and …

MySQL recently released 5.1.20 beta. I just ran into another gotcha, which prompted me to post this draft I’ve had for a while.

rbradford@newyork:/opt/mysql51$ scripts/mysql_install_db
Installing MySQL system tables...
070709 23:24:08 [Note] Plugin 'InnoDB' disabled by command line option
OK
Filling help tables...
070709 23:24:08 [Note] Plugin 'InnoDB' disabled by command line option
OK

To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system

PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
./bin/mysqladmin -u root password 'new-password'
./bin/mysqladmin -u root -h newyork password 'new-password'
See the manual for more instructions.
You can start the MySQL daemon with:
cd . ; ./bin/mysqld_safe &

You can test the MySQL daemon with mysql-test-run.pl
cd …

I’m at some internal MySQL training today at our US HQ. In a room of 11 people we are all using our laptops for access to additional machines. The beauty of this is we have Linux (Ubuntu 5.10, 6.10, 7.04, Red Hat Fedora), Mac OS/X and Windows Operating Systems on various staff machines. It’s great to realize we are not locked into just one infrastructure, and we have the ability to all do our work effectively and MySQL works just as well across these technologies. I can’t however SSH from my iPhone yet, unlike my previous Nokia E62 PDA.

Tonight I spoke at the NY MySQL Meetup. The topic “Practical Performance Tips & Tricks” was a full packed 1 hour session, with 4 x 15 minute sections on Beginner, Intermediate, Advanced and MySQL Proxy. The goal to hopefully cover content for different level of attendees. This meeting followed up the large turnout from last month’s meeting with at least 35 people. Thanks again to Logicworks for sponsoring the night and providing the beer and food, especially to adjust for the late arriving presenter.

My Slides are download able in PDF format here.

Some additional links that were discussed during the meeting for reference included.

…

I was playing with the 5 sample tutorial Lua scripts available here with the MySQL Proxy, but I was doing something a little inefficiently.

I started mysqld, then I started the MySQL Proxy with the lua script, then connected to MySQL via the proxy. To test a different script I was actually killing the MySQL Proxy and restarting with appropriate script, but this is unnecessary. MySQL Proxy will re-read the lua script, as specified with –proxy-lua-script on new connection. All I need to do is copy in the file in question and get a new mysql client connection.

The tech version of the right way:

$ cp tutorial-basic.lua running.lua
$ ./mysql-proxy --proxy-lua-script=running.lua &
$ mysql -uusr -p -P4040 -h127.0.0.1
mysql> # do my stuff
mysql> exit;
$ cp …

MySQL uses disk. Ok, so everybody knew that. MySQL uses disk in two primary ways.

• Random I/O (Reading & Writing Data/Index blocks)
• Sequential I/O (Binary Log, InnoDB Redo Log)

Historically it’s been best practice to separate these onto different spindles, and also separating the OS and tmp space onto a third spindle. With commodity H/W that can be easily done, but today a lot of people use SAN. Is this a good thing for a MySQL Database?
That’s a topic of much discussion at a later time, however I’ll add two points. A lot of SAN configurations are RAID 5, and RAID 10 is a better choice due to removing the requirement to calculate the parity. Second, last week I observed a RAID disk failure and it took an incredible long time for the disk to be re-built. Just how many SAN uses our there have actually timed a disk rebuild on a loaded system and seen the impact on the system in general.