The log buffer writes redo log information to ib_logfile0 and ib_logfile1 for transactional purposes only. There is nothing text readable within those files.

The file /var/log/mysqld.log is the main error-logging mechanism built in mysql. Anything additional would probably be in /var/log/messages.

You could use the general log. In fact, you should try using the MySQL table version of the general log.

If you run this:

SHOW CREATE TABLE mysql.general_log\G

You should see something like this:

mysql> show create table mysql.general_log\G
*************************** 1. row ***************************
       Table: general_log
Create Table: CREATE TABLE `general_log` (
  `event_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `user_host` mediumtext NOT NULL,
  `thread_id` int(11) NOT NULL,
  `server_id` int(10) unsigned NOT NULL,
  `command_type` varchar(64) NOT NULL,
  `argument` mediumtext NOT NULL
) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='General log'
1 row in set (0.14 sec)

mysql>

The user_host column will record the MySQL user and the IP Address/DNS Name the command came from.

You are probably saying right now, "That table is a CSV file. I would have to parse it." That's true, you would have to. However, did you know that you can convert it to a MyISAM table? I have actually tried this out for one of my employer's DB Hosting Clients, and I wrote a post explaining it (See the Feb 24, 2011 post down below).

Here are the basic steps:

1. Make the mysql.general_log table MyISAM

   Run the following:

   CREATE TABLE mysql.general_log_original LIKE mysql.general_log;
   ALTER TABLE mysql.general_log ENGINE=MyISAM;
   ALTER TABLE mysql.general_log ADD INDEX (event_time);
   

2. Enable the general log

   Add the following to /etc/my.cnf

   [mysqld]
   log-output=TABLE
   general-log
   

   If you also want the text version of the general log, add this:

   [mysqld]
   log-output=TABLE,FILE
   general-log
   general-log-file=/var/log/mysql_general.log
   

3. Restart mysql

   Simply run service mysql restart

I have many posts about using the general log and the slow log as MyISAM tables:

• Jan 22, 2013 : How often does the slow_log table get updated in MySQL?
• Nov 10, 2012 : Redirecting MySQL errors and slow logs into another database
• Jan 08, 2012 : How to enable MySQL general log?
• Dec 27, 2011 : How to do MySQL User Accounting
• Nov 18, 2011 : Create a custom log table in MySQL
• Jun 30, 2011 : How do I output MySQL logs to syslog?
• Feb 24, 2011 : Audit logins on MySQL database

CAVEAT

MySQL 5.5.28 has recently introduced the audit log plugin and how to install it.

Here are the options

• audit-log-buffer-size
• audit-log
• audit-log-file
• audit-log-flush
• audit-log-policy
• audit-log-rotate-on-size
• audit-log-strategy

These are new to me so I have nothing pros or cons at this time on the Audit Log Plugin.