Log levels

OceanBase Database supports seven log levels. The following table describes the log levels in descending order.

You can execute the SHOW PARAMETERS statement to query the current log level. The default log level is WDIAG.

obclient> SHOW PARAMETERS LIKE '%syslog_level%';

The return result is as follows:

+-------+----------+----------------+----------+--------------+-----------+-------+------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+---------------+-----------+
| zone  | svr_type | svr_ip         | svr_port | name         | data_type | value | info                                                                                                                         | section  | scope   | source  | edit_level        | default_value | isdefault |
+-------+----------+----------------+----------+--------------+-----------+-------+------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+---------------+-----------+
| zone1 | observer | 172.xx.xxx.xxx |     2882 | syslog_level | NULL      | WDIAG | specifies the current level of logging. There are DEBUG, TRACE, WDIAG, EDIAG, INFO, WARN, ERROR, seven different log levels. | OBSERVER | CLUSTER | DEFAULT | DYNAMIC_EFFECTIVE | WDIAG         |         1 |
+-------+----------+----------------+----------+--------------+-----------+-------+------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+---------------+-----------+
1 row in set

OceanBase Database allows you to set the log level to obtain more accurate logs. You can set the log level at three levels: system, session, and statement. When printing logs, the priority from high to low is statement, session, and system. OceanBase Database also allows you to specify the log level by module.

• System level: The scope is all OBServer nodes in the entire cluster. You can configure this level only in the sys tenant.
• Session level: The scope is the OBServer nodes where the current tenant is located in the cluster.
  • A session-level variable takes effect only on the current session and not on other sessions.
  • A global variable does not take effect on the current session; you need to log in again to establish a new session for it to take effect.
• Statement level: The scope is the OBServer node where the current statement is executed. The level takes effect only during SQL statement execution.

The following section describes how to set the log level at the system, session, and statement levels.

• Set the log generation level for the entire system.

  You can use one of the following methods:

  • Use the syslog_level system parameter. For example, you can set the log generation level of the SQL module to DEBUG and that of the COMMON module to ERROR.

      obclient > ALTER SYSTEM SET syslog_level='sql.*:debug, common.*:error';
    

  • Run the bash kill -41/42 $pid command in the operating system.

    In the command, kill -41 is used to lower the level of program logs. For example, the current level of program logs is INFO. The log level is lowered to TRACE after you run the kill -41 command. kill -42 is used to raise the level of program logs. For example, the current level of program logs is INFO. The log level is raised to WARN after you run the kill -42 command.

    We recommend that you use the syslog_level system parameter. This is because when OceanBase Database refreshes configurations, it loads the syslog_level value specified in the observer.config.bin file in the etc/ directory, and thus the kill command is invalid.

    Notice

    We recommend that you use the kill -41 or kill -42 command to adjust the log level only when you cannot log in to the OceanBase cluster from the SQL client.

• Set the log generation level for the current session.

  You can use the ob_log_level system parameter to set the log generation level. For example, you can set the log generation level of the SQL module to DEBUG and that of the COMMON module to INFO.

  obclient > SET @@ob_log_level='sql.*:debug, common.*:info';
  

• Set the log generation level for the current statement.

  You can use a hint to set the log generation level. For example, you can set the log generation level of the SQL module to DEBUG and that of the COMMON module to INFO. For more information about hints, see Optimizer hints.

  obclient > SELECT /*+log_level('sql.*:debug, common.*:info')*/ * FROM t;
  

  Note

  If you want to execute SQL statements containing hints in a MySQL client, you must log in to the client by using the -c option. Otherwise, the MySQL client will remove the hints from the SQL statements as comments, and the system cannot receive the hints.