Modifying Parameters of a DB Instance

You can modify parameters of a DB instance to optimize performance if needed.

Precautions

To ensure DB instance stability, you can only modify the parameters that are available on the console.
To apply certain parameter modifications, you need to reboot the DB instance. After you modify a parameter value, check the value in the Effective upon Reboot column. You are advised to perform the operation during peak-off hours.
Figure 1 Parameter list

The value of validate_password.length cannot be smaller than that of validate_password.number_count+validate_password.special_char_count+(2 * validate_password.mixed_case_count). Otherwise, the allowed minimum value of validate_password.length is used when the parameter template is applied.
If you want to use a custom parameter template during instance creation, ensure that the value of validate_password.length in the template is at most 16. Otherwise, the DB instance fails to be created.
If you want to use a custom parameter template during instance creation, ensure that the values of validate_password.mixed_case_count, validate_password.number_count, and validate_password.special_char_count are at most 4. Otherwise, the DB instance may fail to be created. The default value 1 is recommended.
The value of rds_compatibility_mode depends on the GaussDB(for MySQL) kernel version.

Modifying Parameters of a DB Instance

Log in to the management console.
Click in the upper left corner and select a region and project.
Click in the upper left corner of the page and choose Databases > GaussDB(for MySQL).
On the Instances page, click the instance name.
In the navigation pane, choose Parameters. On the displayed page, modify parameters as required.

Figure 2 Modifying parameters of a DB instance
- To save the modifications, click Save. In the displayed dialog box, click Yes.
- To cancel the modifications, click Cancel.
- To preview the modifications, click Preview.
After the parameters are modified, click Change History to view the modification records.

Figure 3 Viewing the modification records

Modifying Parameters in a Parameter Template

You can modify parameters in a custom parameter template and then apply the template to multiple DB instances.

In the navigation pane, choose Parameter Templates. On the Custom Templates tab, click the parameter template name.
On the displayed Parameters page, modify parameters as required.

Figure 4 Modifying parameters in a parameter template
- To save the modifications, click Save. In the displayed dialog box, click Yes.
- To cancel the modifications, click Cancel.
- To preview the modifications, click Preview.
After the parameters are modified, click Change History to view the modification records.
After a parameter template is modified, the modification will not take effect until the template is applied to DB instances. On the Parameter Templates page, locate the parameter template you want to apply and choose More > Apply in the Operation column.

Figure 5 Applying a parameter template to a DB instance
Select one or more DB instances and click OK.

Figure 6 Selecting DB instances
After the parameter template is applied, click the DB instance name and check whether the parameters have been modified on the Parameters page.

Common Parameters

**Table 1** Common parameters
Parameter	Description	Reference
time_zone	Specifies the time zone of the server.	How Do I Change the Time Zone?
default_password_lifetime	Specifies the global automatic password expiration policy, in days.	How Do I Configure a Password Expiration Policy for GaussDB(for MySQL) Instances?
character_set_server	Specifies the server character set.	How Do I Use the utf8mb4 Character Set to Store Emojis in a GaussDB(for MySQL) Instance?
collation_server	Specifies the collation for the character set of the server. The collation must match the character set specified by character_set_server. Otherwise, the database cannot be started or restarted.	-
group_concat_max_len	Specifies the maximum permitted result length in bytes for the GROUP_CONCAT() function.	-
max_connections	Specifies the maximum number of concurrent client connections. If this parameter is set to default, the parameter value depends on how much memory there is.	What Is the Maximum Number of Connections to a GaussDB(for MySQL) Instance?
max_prepared_stmt_count	Limits the total number of prepared statements in the server. Too many statements may cause the server to run out of memory (OOM) and risk denial-of-service attacks. Configure this parameter as needed.	-
innodb_flush_log_at_trx_commit	Controls the balance between strict ACID compliance for commit operations, and higher performance that is possible when commit-related I/O operations are rearranged and done in batches. When this parameter is set to 0, the content of the InnoDB log buffer is written to the log file approximately once per second and the log file is flushed to disk. The default value of 1 is required for full ACID compliance. With this value, the contents of the InnoDB log buffer are written out to the log file at each transaction commit and the log file is flushed to disk. When this parameter is set to 2, the contents of the InnoDB log buffer are written to the log file after each transaction commit and the log file is flushed to disk approximately once per second.	Viewing Suggestions on GaussDB(for MySQL) Parameter Tuning
sql_mode	Specifies the SQL server mode.	-
binlog_expire_logs_seconds	Specifies the binary log expiration period in seconds. After their expiration period ends, binary log files can be automatically removed.	-