This topic describes how to modify the parameters of an ApsaraDB RDS for MySQL instance in the ApsaraDB RDS console or by using the ApsaraDB RDS API. This topic also describes how to view the parameter modification history in the ApsaraDB RDS console.
For more information about how to view the parameter settings of an RDS instance, see View the parameters of an ApsaraDB RDS for MySQL instance.
Precautions
- To ensure the stability of your RDS instance, you can modify only the parameters that are displayed in the ApsaraDB RDS console.
- When you modify the parameters of your RDS instance, you can view the value range of each parameter in the Value Range column on the Editable Parameters tab of the Parameters page in the ApsaraDB RDS console.
- The new values of some parameters take effect only after you restart your RDS instance. For more information, view the Force Restart column on the Editable Parameters tab of the Parameters page in the ApsaraDB RDS console. We recommend that you modify parameters during off-peak hours and make sure that your application is configured to automatically reconnect to your RDS instance.
- If read-only RDS instances are attached to a primary RDS instance, the modifications to some parameters of the primary RDS instance are automatically synchronized to the read-only RDS instances. For more information, see Appendix: Parameters to be synchronized to read-only RDS instances.
Modify parameters
View the parameter modification history
- Access RDS Instances, select a region at the top, and then click the ID of the target RDS instance.
- In the left-side navigation pane, click Parameters.
- On the page that appears, click the Edit History tab.
- Select a time range and click OK.
Configure parameters by using expressions
You can set a parameter to an expression for an RDS instance. If you set an instance type-related parameter to an expression, the value of the parameter dynamically changes when the instance type changes. This ensures the stability of the RDS instance.
In the example shown in the following figure, the innodb_buffer_pool_size parameter
is set to {DBInstanceClassMemory*3/4}
. If the value of the DBInstanceClassMemory variable changes, the value of the innodb_buffer_pool_size
parameter dynamically changes, and you do not need to manually change the value.

The following table describes the supported expression syntax.
Category | Description | Example |
---|---|---|
Variables |
Note
|
{DBInstanceClassMemory*3/4} |
Operators |
|
|
Functions |
|
LEAST({DBInstanceClassMemory/256},10485760) |
Modify the parameters of multiple RDS instances at a time
FAQ
- After I modify the parameters of my RDS instance, do the new values of the parameters
immediately take effect? Do I need to restart my RDS instance?
After you modify the parameters of your RDS instance, the new values of some parameters take effect in approximately 5 minutes even if you do not restart your RDS instance. However, the new values of some parameters take effect only after you restart your RDS instance. For more information, view the Force Restart column on the Editable Parameters tab of the Parameters page in the ApsaraDB RDS console.
- After I modify the parameters of my RDS instance, why do the new values of the parameters
not take effect?
After you modify the parameters of your RDS instance, you must click Apply Changes on the Editable Parameters tab on the Parameters page in the ApsaraDB RDS console to make the new values of the parameters take effect.
Appendix: Parameters to be synchronized to read-only RDS instances
If read-only RDS instances are attached to a primary RDS instance, the modifications to some parameters of the primary RDS instance are automatically synchronized to the read-only RDS instances. The following list provides these parameters.
- lower_case_table_names
Note If your RDS instance runs MySQL 8.0, you cannot change the value of this parameter.
- innodb_large_prefix
Related operations
Operation | Description |
---|---|
Modify parameters of an ApsaraDB for RDS instance | Modifies the parameters of an ApsaraDB RDS instance. |
Query the parameter template of an ApsaraDB for RDS instance | Queries the parameter templates that are available for an ApsaraDB RDS instance. |
Query parameter configurations | Queries the parameter settings of an ApsaraDB RDS instance. |