SQL Error Log Plugin

Documentation for the SQL Error Log Plugin, which allows logging of errors sent to clients to a file, enabling analysis of application-side errors that might otherwise be missed.

The SQL_ERROR_LOG plugin collects errors sent to clients in a log file defined by sql_error_log_filename, so that they can later be analyzed. The log file can be rotated if sql_error_log_rotate is set.

Errors are logged as they happen and an error will be logged even if it was handled by a condition handler and was never technically sent to the client.

From MariaDB 10.11.5 warnings can also be logged if sql_error_log_warnings is enabled.

Comments are also logged, which can make the log easier to search. But this is only possible if the client does not strip the comments away. For example, the mariadb command-line client only leaves comments when started with the --comments option.

Installing the Plugin

Although the plugin's shared library is distributed with MariaDB by default, the plugin is not actually installed by MariaDB by default. There are two methods that can be used to install the plugin with MariaDB.

The first method can be used to install the plugin without restarting the server. You can install the plugin dynamically by executing INSTALL SONAME or INSTALL PLUGIN. For example:

INSTALL SONAME 'sql_errlog';

The second method can be used to tell the server to load the plugin when it starts up. The plugin can be installed this way by providing the --plugin-load or the --plugin-load-add options. This can be specified as a command-line argument to mariadbd or it can be specified in a relevant server option group in an option file. For example:

[mariadb]
...
plugin_load_add = sql_errlog

Uninstalling the Plugin

You can uninstall the plugin dynamically by executing UNINSTALL SONAME or UNINSTALL PLUGIN. For example:

UNINSTALL SONAME 'sql_errlog';

If you installed the plugin by providing the --plugin-load or the --plugin-load-add options in a relevant server option group in an option file, then those options should be removed to prevent the plugin from being loaded the next time the server is restarted.

Logging

The log format until MariaDB 10.10 is:

Time User Error_code: Error_message : Query

Starting from MariaDB 10.11, the format is:

Time User Type Error_code: Error_message : Query

Starting from MariaDB 10.6.17, MariaDB 10.11.7, MariaDB 11.0.5, MariaDB 11.1.4, MariaDB 11.2.3, MariaDB 11.3.2, and MariaDB 11.4.1, when the sql_error_log_with_db_and_thread_info variable is enabled, the log also contains thread id and database name. If there is no database, NULL will be displayed.

Time Thread_id User Database_name Type Error_code: Error_message : Query

Each separated by a space or : as above

Option	Description	Version
Time	Time (YYYY-MM-DD hh-mm-ss)	5.5.22
Thread Id	Thread Id of current thread	10.6.17
User	privilege_user [login_user_name] @ hostname [ip]	5.5.22
Database name	Name of the currently selected database	10.6.17
Type	ERROR or WARNING	10.11.6
Error_code	OS error, MariaDB storage engine code (120-199) or MariaDB internal error code (1000-)	5.5.22
Query	Query text	5.5.22

Example of Logs

2023-10-31 15:54:37 root[root] @ localhost [] ERROR 1146: Table 'test.t_doesnt_exist' doesn't exist : select * from t_doesnt_exist
2023-10-31 15:54:37 root[root] @ localhost [] ERROR 1064: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'syntax_error_query' at line 1 : syntax_error_query
2023-10-31 15:54:37 root[root] @ localhost [] ERROR 1146: Table 'test.temptab' doesn't exist : SELECT `c` FROM `temptab`
2023-11-01 11:31:15 [monty] @ storm [192.168.0.12] ERROR 1051: Unknown table 'test.t1' : drop table t1

With sql_error_log_with_db_and_thread_info enabled (database test and thread id 4):

2023-10-31 15:54:37 4 root[root] @ localhost [] `test` ERROR 1146: Table 'test.t_doesnt_exist' doesn't exist : select * from t_doesnt_exist

Example Usage

install plugin SQL_ERROR_LOG soname 'sql_errlog';
Query OK, 0 rows affected (0.00 sec)

USE test;

SET sql_mode='STRICT_ALL_TABLES,NO_ENGINE_SUBSTITUTION';
Query OK, 0 rows affected (0.00 sec)

CREATE TABLE foo2 (id INT) ENGINE=WHOOPSIE;
ERROR 1286 (42000): Unknown storage engine 'WHOOPSIE'
\! cat data/sql_errors.log
2013-03-19  9:38:40 msandbox[msandbox] @ localhost [] ERROR 1286: Unknown storage engine 'WHOOPSIE' : CREATE TABLE foo2 (id int) ENGINE=WHOOPSIE

Versions

Version	Status	Introduced
1.1	Stable	MariaDB 10.6.17, MariaDB 10.11.7, MariaDB 11.0.5, MariaDB 11.1.4, MariaDB 11.2.3
1.0	Stable	MariaDB 10.1.13
1.0	Gamma	MariaDB 10.0.10
1.0	Alpha	MariaDB 5.5.22

System Variables and Options

• sql_error_log

• sql_error_log_filename

• sql_error_log_rate

• sql_error_log_rotate

• sql_error_log_rotations

• sql_error_log_size_limit

• sql_error_log_size_warnings

• sql_error_log_with_db_and_thread_info

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