Modifying Parameters of an RDS for MySQL Instance

You can change parameter values in a custom parameter template and apply it to optimize RDS database performance.

You can only change the values in custom parameter templates. You cannot change the values in default parameter templates.

Keep in mind the following points before modifying the parameters:

Modifying instance parameters: If you modify dynamic parameters on the Parameters page of a DB instance and save the modifications, the modifications take effect immediately regardless of the Effective upon Reboot setting. However, if you modify static parameters on the Parameters page of a DB instance and save the modifications, the modifications do not take effect until you manually reboot the DB instance.
Modifying parameter template parameters: If you modify parameters in a custom parameter template on the Parameter Templates page and save the modifications, the modifications do not take effect until you apply the template to your DB instances. If you modify static parameters in a custom parameter template on the Parameter Templates page and save the modifications, the modifications do not take effect until you apply the template to your DB instances and manually reboot those DB instances. For details, see Applying a Parameter Template.

Global parameters can only be modified on the console. Session-level parameters can be modified using SQL statements. When you modify a parameter, the time when modifications take effect varies with the parameter type.

The RDS console displays the statuses of DB instances that the parameter template applies to. For example, if the DB instance has not yet used the latest modifications made to its parameter template, its status is Parameter change. Pending reboot. You need to manually reboot the DB instance for the latest modifications to take effect for that DB instance.

For better parameter modification experience, you are advised to upgrade the minor version of your DB instance to the latest.

RDS has default parameter templates whose parameter values cannot be changed. You can view these parameter values by clicking the default parameter templates. If a custom parameter template with incorrect settings is applied to a DB instance, this instance may fail to start. If this happens, you can re-configure the custom parameter template based on the settings of the default parameter template.

Modifying a Custom Parameter Template and Applying It to a DB Instance

Log in to the management console.
Click in the upper left corner and select a region and a project.
Click in the upper left corner of the page and choose Databases > Relational Database Service.
Choose Parameter Templates in the navigation pane on the left. On the Custom Templates page, click the target parameter template.
On the Parameters page, modify parameters as required.
For parameter details, see Suggestions on RDS for MySQL Parameter Tuning.

Available operations are as follows:

Figure 1 Modifying parameters in a parameter template
- To save the modifications, click Save.
- To cancel the modifications, click Cancel.
- To preview the modifications, click Preview.
  Figure 2 Previewing changes
Click Change History to view the changes.
Apply the parameter template to your DB instance. For details, see Applying a Parameter Template.
View the status of the DB instance to which the parameter template has been applied.
If the DB instance status is Parameter change. Pending reboot, you need to reboot the DB instance for the modifications to take effect.
- The DB instance reboot caused by instance class changes will not make parameter modifications take effect.
- If you have modified parameters of a primary DB instance, you need to reboot the primary DB instance for the modifications to take effect. (For primary/standby DB instances, the parameter modifications are also applied to the standby DB instance.)
- If you have modified parameters of a read replica, you need to reboot the read replica for the modifications to take effect.

Modifying Parameters of a DB Instance

Log in to the management console.
Click in the upper left corner and select a region and a project.
Click in the upper left corner of the page and choose Databases > Relational Database Service.
On the Instances page, click the target DB instance.
In the navigation pane on the left, choose Parameters. On the displayed page, modify parameters as required.
Check the value in the Effective upon Reboot column.
- If the value is Yes and the DB instance status on the Instances page is Parameter change. Pending reboot, a reboot is required for the modifications to take effect.
  
  If you have modified parameters of a primary DB instance, you need to reboot the primary DB instance for the modifications to take effect. (For primary/standby DB instances, the parameter modifications are also applied to the standby DB instance.)
  
  If you have modified parameters of a read replica, you need to reboot the read replica for the modifications to take effect.
- If the value is No, the modifications take effect immediately.
Figure 3 Parameters
- To save the modifications, click Save.
- To cancel the modifications, click Cancel.
- To preview the modifications, click Preview.
After parameters are modified, you can click Change History to view parameter modification details.

Modifying Parameters of Multiple DB Instances at a Time

Log in to the management console.
Click in the upper left corner and select a region and a project.
Click in the upper left corner of the page and choose Databases > Relational Database Service.
On the Instances page, select the DB instances with the same DB engine of the same version and choose More > Modify Parameters above the DB instance list.
On the Modify Parameters page, select the parameters you want to modify, change the parameter values, and click Apply.
A maximum of 30 parameters can be modified at a time. Only selected parameters will be applied to your DB instances. The modified parameters are automatically selected. You can also deselect them.
Check the value in the Effective upon Reboot column.
- If the value is Yes and the DB instance status on the Instances page is Parameter change. Pending reboot, a reboot is required for the modifications to take effect.
  
  If you have modified parameters of a primary DB instance, you need to reboot the primary DB instance for the modifications to take effect. (For primary/standby DB instances, the parameter modifications are also applied to the standby DB instance.)
  
  If you have modified parameters of a read replica, you need to reboot the read replica for the modifications to take effect.
- If the value is No, the modifications take effect immediately.
Figure 4 Modifying parameters
In the displayed dialog box, click OK.

Figure 5 Confirming parameter changes
After the parameters are modified, click the Parameter Changes tab on the Parameter Templates page to view details about the modified parameters.

Common Parameters

**Table 1** Common parameters
Parameter	Description	Reference
time_zone	The time zone. Keep the value of this parameter for read replicas the same as that for the primary instance.	How Can I Change the Time Zone?
default_password_lifetime	The global automatic password expiration policy, in days.	How Do I Configure a Password Expiration Policy for RDS for MySQL DB Instances?
tx_isolation	The default transaction isolation level.	How Do I Change the RDS Transaction Isolation Level?
character_set_server	The server character set.	How Do I Use the utf8mb4 Character Set to Store Emojis in an RDS for MySQL DB Instance?
lower_case_table_names	The case sensitivity of table names. If this parameter is set to 0, table names are stored as specified and are case sensitive. If it is set to 1, table names are stored in lowercase and are case insensitive.	How Do I Set Case Sensitivity for RDS for MySQL Table Names?
group_concat_max_len	The maximum permitted result length in bytes for the GROUP_CONCAT() function.	Incorrect GROUP_CONCAT Results
max_connections	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 an RDS DB Instance?