sudo tcpdump -i lo -s 0 -l -w - dst port 3306 | strings | perl -e '
while(<>) { chomp; next if /^[^ ]+[ ]*$/;
  if(/^(SELECT|UPDATE|DELETE|INSERT|SET|COMMIT|ROLLBACK|CREATE|DROP|ALTER)/i) {
    if (defined $q) { print "$q\n"; }
    $q=$_;
  } else {
    $_ =~ s/^[ \t]+//; $q.=" $_";
  }
}'

This will only work for clients communicating via TCP – if you are connecting through ‘localhost’ you will be going through a unix socket instead. If you switch ‘localhost’ to ’127.0.0.1′ then your queries will go through the network stack.

If you just want to dump the traffic to a file for a little bit and analyze it later, do this instead:

sudo tcpdump -i lo port 3306 -s 65535 -x -n -q -tttt> tcpdump.out

You can then use mk-query-digest from Maatkit with–type=tcpdump. See more about this at the MySQL Performance Blog.

ERROR: While executing gem … (Gem::Installer::ExtensionBuildError)
ERROR: Failed to build gem native extension.
 
ruby extconf.rb update
checking for mysql_query() in -lmysqlclient… no
...

After much hairpulling, two hyphens solved my problem:

sudo gem install mysql -- \
--with-mysql-include=/usr/include/mysql \
--with-mysql-lib=/usr/lib/mysql

A blog comment I found explains the double hyphens:

The double hyphens (–) tells the option parser that there is no more options on the command line. This special syntax comes from GNU getopt. Everything after ‘–’ is treated as non-options. This is useful if you want to write something on the command line that looks like an option but is not, or if it should be parsed though as an option to another program called by the one you are calling.

The two hyphens in this particular command string is important since the gem binary must not confuse the ‘–with-mysql-dir’ option as an option for gem it self. Instead this option should be passed on to the make command called in the gem internals.

Thomas Watson

And if you are on a 64-bit system, be sure to use –-with-mysql-lib=/usr/lib64/mysql instead.

#!/bin/bash
 
EXPECTED_ARGS=3
E_BADARGS=65
MYSQL=`which mysql`
 
Q1="CREATE DATABASE IF NOT EXISTS $1;"
Q2="GRANT ALL ON *.* TO '$2'@'localhost' IDENTIFIED BY '$3';"
Q3="FLUSH PRIVILEGES;"
SQL="${Q1}${Q2}${Q3}"
 
if [ $# -ne $EXPECTED_ARGS ]
then
  echo "Usage: $0 dbname dbuser dbpass"
  exit $E_BADARGS
fi
 
$MYSQL -uroot -p -e "$SQL"

To use it, just run:

./createdb testdb testuser secretpass

That command would create a database named testdb, and user testuser with the password of secretpass.

To fix these, create or edit the following file:

vi /etc/munin/plugin-conf.d/cpanel.conf

It should contain the following:

[mysql*]
user root
group wheel
env.mysqladmin /usr/bin/mysqladmin
env.mysqlopts --defaults-extra-file=/root/.my.cnf

This would load the username and password from root’s mysql config. If that file doesn’t exist you can create it:

sudo vi /root/.my.cnf

[client]
user="root"
pass="secret!password"

Now just restart Munin, wait a a little bit, and the graphs should start populating again!

sudo /etc/init.d/munin-node restart

The following command will find all MyISAM tables from a certain database and convert them to InnoDB:

mk-find <db_name> --engine MyISAM --exec "ALTER TABLE %D.%N ENGINE=INNODB" --print

You can download the latest version from Maatkit’s Google Code page.