Modify parameters of an ApsaraDB RDS for MySQL instance - ApsaraDB RDS

This topic describes how to modify the parameters of an ApsaraDB RDS for MySQL instance in the ApsaraDB RDS console or by calling an API operation to meet your business requirements. 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.

Usage notes

To ensure the stability of your RDS instance, you can modify only the parameters that are displayed in the ApsaraDB RDS console.
Note
In the ApsaraDB RDS console, some parameters are read-only parameters, and the values of the read-only parameters cannot be modified.
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 Modifiable 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. You can check the values in the Force Restart column on the Modifiable Parameters tab of the Parameters page in the ApsaraDB RDS console to view the parameters. We recommend that you configure 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.
In MySQL 8.0, the value of the lower_case_table_names parameter is fixed as 1.

Modify parameters

Modify the parameters of an RDS instance

Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.
In the left-side navigation pane, click Parameters.

Perform the following operations:

Modify a single parameter.
1. On the Modifiable Parameters tab, find the parameter that you want to modify and change its value based on your business requirements.
  - In the Running Value column, click the icon. In the dialog box that appears, enter the new value based on the value range of the parameter.
  - Select a parameter value from the drop-down list in the Running Value column.
2. Click OK.
3. Click Apply Parameters. In the dialog box that appears, select the time range during which you want the new parameter settings to take effect. You can select Take Effect Immediately, Take Effect Within the Maintenance Window, or Take Effect at Specified Time.
  Important
  - If the new parameter settings take effect only after you restart the RDS instance, the system prompts you to restart the RDS instance. We recommend that you restart the RDS instance during off-peak hours and make sure that your application is configured to automatically reconnect to the RDS instance.
  - Before the new parameter values take effect, you can click Cancel Changes to revoke the changes.
Apply a parameter template to the RDS instance.
The system provides various system parameter templates to meet the requirements of different business scenarios, such as scenarios in which you require high performance. You can also create custom parameter templates to configure multiple parameters at a time. For more information, see Use a parameter template.
Important
If the parameter template takes effect only after you restart the RDS instance, we recommend that you apply the parameter template during off-peak hours and make sure that your application is configured to automatically reconnect to the RDS instance.
1. On the Modifiable Parameters tab, click Apply Template.
2. In the Apply Template dialog box, select the parameter template that you want to use and click OK.
  Note
  - You can view the number of parameters in the parameter template and check whether you must restart the RDS instance for the new values of the parameters to take effect. You can also click View Parameter Change to view the changes in the values of the parameters in the parameter template.
  - If you cannot find the parameter template that you want to use, you must check whether the parameter template resides in the same region as the RDS instance. If the parameter template and the RDS instance reside in different regions, you can replicate the parameter template to the region where the RDS instance resides. For more information, see Use a parameter template.

Export the parameter settings of the RDS instance as a parameter template

On the Modifiable Parameters tab, click Export as Template.

Configure the following parameters. 导出为模板参数设置

Parameter	Description
Template Name	Enter a template name. The name must be 8 to 64 characters in length and can contain letters, digits, dots (.), and underscores (_). The name must start with a letter.
Description	Enter a description for the parameter template. The description can be up to 200 characters in length.

Click OK. A parameter template is created in the region.

Export the parameter settings of the RDS instance to your computer and import the parameter settings after the modification
On the Modifiable Parameters tab, click Export Parameters. The parameter settings of the RDS instance are exported to your computer as a TXT file.
1. Modify the parameters in the TXT file. Then, click Import Parameters. In the Import Parameters dialog box, copy the parameter settings from the TXT file and paste them to the dialog box.
2. Click OK.
3. Click Apply Changes. In the dialog box that appears, select the time range during which you want the new parameter settings to take effect. You can select Take Effect Immediately, Take Effect Within Maintenance Window, or Take Effect at Specified Time.
  Important
  - If the new parameter settings take effect only after you restart the RDS instance, the system prompts you to restart the RDS instance. We recommend that you restart the RDS instance during off-peak hours and make sure that your application is configured to automatically reconnect to the RDS instance.
  - Before the new parameter values take effect, you can click Cancel Changes to revoke the changes.
  - If an error message that indicates invalid parameter formats appears, you must check whether the new parameter value is within the value range of the parameter.

Modify the parameters of multiple RDS instances at a time

Log on to the ApsaraDB RDS console. In the left-side navigation pane, click Instances. In the top navigation bar, select the region in which your RDS instance resides.
Select the RDS instances for which you want to modify parameters and click Modify Parameters below the instance list.
Note
The RDS instances must run the same database engine version and RDS edition. Otherwise, the Modify Parameters button is dimmed.
In the Parameter Settings dialog box, click the icon on the right of the parameter that you want to modify.
In the Current Value column, select or enter a new value. Then, click OK.
In the Parameter Settings dialog box, confirm the new value and click OK.

View the parameter configuration history

Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.
In the left-side navigation pane of the page that appears, 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 your 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.

In the following example, 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.

表达式语法

The following table describes the supported expression syntax.

Category	Description	Example
Variables	AllocatedStorage: specifies the storage capacity of an RDS instance. The value of this variable is an integer. DBInstanceClassMemory: specifies the available memory capacity of an RDS instance. The value of this variable is calculated by deducting the memory that is occupied by the control processes on the instance from the memory capacity that is supported by the instance type. The value of this variable is an integer. For example, if the memory capacity that is supported by the instance type is 16 GB and the memory that is occupied by the control processes is 4 GB, the value of the DBInstanceClassMemory variable is 12 GB. DBInstanceClassCPU: specifies the number of cores that are supported by the instance type. The value of this variable is an integer. DBInstanceClassConnections: specifies the maximum number of connections that are supported by the instance type. The value of this variable is an integer. Note For more information about the instance types and the storage capacity, memory capacity, number of cores, and maximum number of connections that are supported by each instance type, see Primary ApsaraDB RDS instance types. For more information about how to configure the innodb_buffer_pool_size parameter of an RDS instance, see Background information. The memory that is occupied by control processes is the smaller value between the values that are calculated by using the following formulas: Memory capacity supported by the instance type × 0.65 and (Memory capacity supported by the instance type/16384 + 1) × 2048.	{DBInstanceClassMemory*3/4}
Operators	Expression syntax: An expression is enclosed by a pair of braces `{}`. Division operator (/): This operator is used to divide a number by another number. If the quotient is a decimal, only the integer part of the quotient is returned. The dividend and the divisor must be integers. For example, ApsaraDB RDS can process {DBInstanceClassMemory3/4} but not {DBInstanceClassMemory0.75}. Multiplication operator (*): This operator is used to multiply a number by another number. If the product is a decimal, only the integer part of the product is returned. The two numbers must be integers.	{DBInstanceClassMemory*3/4}
Functions	The GREATEST() function returns the largest value among an array of integers or the largest value that is calculated by an array of expressions. The LEAST() function returns the smallest value from an array of integers or the smallest value from an array of values calculated by an array of expressions. The SUM() function adds a specified integer or the value that is calculated by a specified expression.	LEAST({DBInstanceClassMemory/256},10485760)

FAQ

After I modify the parameters of my RDS instance, does the modification 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?
Make sure that you click Apply Changes after you modify the parameters.
If a read-only RDS instance runs RDS High-availability Edition, how do I configure parameters for the primary and secondary read-only instances?
You need only to configure parameters for the primary read-only instance. The parameter settings of the primary read-only instance are automatically synchronized to the secondary read-only instance. You cannot modify the parameters of a secondary read-only instance.

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
loose_validate_password_length
default_time_zone
rpl_semi_sync_slave_enabled

Related API operations

Operation	Description
ModifyParameter	Modifies the parameters of an instance.
DescribeParameterTemplates	Queries the parameter templates that are available for an instance.
DescribeParameters	Queries the parameter settings of an instance.