Cluster parameters

In OceanBase Database, you can set parameters to control the features of a cluster, such as load balancing, major compaction time, major compaction mode, resource allocation, and module switches.

You must specify the required parameters when the observer process starts for the first time. For other parameters, the default values are used if you do not specify them. After the process is started, the parameter values are persisted to the observer.config.bin file in the /home/admin/oceanbase/etc directory. You can run the strings observer.config.bin command to view the content in this file. When the process is started the next time, the system reads the parameter values from this file. If no modification is required, you do not need to specify any parameters.

Parameter levels

OceanBase Database provides cluster-level and tenant-level parameters.

• Cluster-level parameters apply to all OBServer nodes in the cluster.

• Tenant-level parameters apply to the OBServer node to which the current tenant belongs.

Parameters whose names start with an underscore (_), such as _ob_max_thread_num, are hidden parameters. Hidden parameters are used by developers only for troubleshooting or emergency O&M. This topic does not describe hidden parameters, nor does it involve any.

Different types of tenants have different privileges regarding querying and modifying parameters, as follows:

The following table describes the data types of parameters in OceanBase Database.

Effective mode of a parameter

Generally, parameters take effect dynamically or upon a restart of the OBServer node. Most parameters take effect dynamically without the need to restart the OBServer node.

View the level and effective mode of a parameter

To view the level and effective mode of a parameter, execute the following statement:

obclient [(none)]> SHOW PARAMETERS LIKE 'max_syslog_file_count';

The query 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 | max_syslog_file_count | INT       | 0     | specifies the maximum number of the log files that can co-exist before the log file recycling kicks in. Each log file can occupy at most 256MB disk space. When this value is set to 0, no log file will be removed. Range: [0, +∞) in integer   | OBSERVER | CLUSTER | DEFAULT | DYNAMIC_EFFECTIVE | 0             |         1 |
+-------+----------+----------------+----------+-----------------------+-----------+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+---------------+-----------+
1 row in set

where

• The value in the scope column indicates the level of the parameter. The value CLUSTER indicates a cluster-level parameter, and the value TENANT indicates a tenant-level parameter.

• The value in the edit_level column indicates the effective mode of the parameter. The value dynamic_effective indicates that the parameter takes effect dynamically, and the static_effective value indicates that the parameter takes effect upon a restart of the OBServer node. Most parameters take effect dynamically without the need to restart the OBServer node.

References

For more information about O&M operations related to cluster parameters, see the following topics:

• View cluster parameters

• Modify cluster parameters