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

Note If you want to modify multiple parameters at a time, we recommend that you use a parameter template. For more information, see Use a parameter template to configure the parameters of ApsaraDB RDS for MySQL instances.
  1. Access RDS Instances, select a region at the top, and then click the ID of the target RDS instance.
  2. In the left-side navigation pane, click Parameters.
  3. Perform the following operations based on your business requirements:
    • Apply a parameter template to the RDS instance.
      Note 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 Editable 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 to configure the parameters of ApsaraDB RDS for MySQL instances.
        Apply Template dialog box
    • Export the parameter settings of the RDS instance as a parameter template in the region that you select.
      1. On the Editable Parameters tab, click Export as Template.
      2. Configure the following parameters. Export as Template dialog box
        Parameter Description
        Template Name The name of the parameter template. The name must be 8 to 64 characters in length and can contain letters, digits, periods (.), and underscores (_). The name must start with a letter.
        Description The description of the parameter template. The description can be up to 200 characters in length.
      3. Click OK.
    • Export the parameter settings of the RDS instance to your computer.

      On the Editable 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. 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 at which you want the new parameter settings to take effect. You can select Take Effect Immediately, Take Effect Within Maintenance Window, or Take Effect Within Specified Time Range.
        Note
        • If the new parameter settings take effect only after you restart the RDS instance, ApsaraDB RDS 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 ApsaraDB RDS prompts you that the operation failed because a new parameter value is in an invalid format, you must check whether the new parameter value is within the Value Range of the parameter.
    • Modify a single parameter of the RDS instance.
      1. On the Editable Parameters tab, find the parameter that you want to modify and click the Edit icon icon in the Running Parameter Value column.
      2. Enter a new value based on the value range that is displayed. Configure a single parameter
      3. Click OK.
      4. Click Apply Changes. In the dialog box that appears, select the time range at which you want the new parameter settings to take effect. You can select Take Effect Immediately, Take Effect Within Maintenance Window, or Take Effect Within Specified Time Range.
        Note
        • If the new parameter settings take effect only after you restart the RDS instance, ApsaraDB RDS 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 value takes effect, you can click Cancel Changes to revoke the change.

View the parameter modification history

  1. Access RDS Instances, select a region at the top, and then click the ID of the target RDS instance.
  2. In the left-side navigation pane, click Parameters.
  3. On the page that appears, click the Edit History tab.
  4. 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.

Expression syntax

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 smallest 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 {DBInstanceClassMemory*3/4} but not {DBInstanceClassMemory*0.75}.
  • 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.
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 among an array of integers or the smallest value that is 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)

Modify the parameters of multiple RDS instances at a time

  1. Log on to the ApsaraDB RDS console. In the left-side navigation pane, click Instances. In the top navigation bar, select the region where the RDS instance resides.
  2. 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 version and edition. Otherwise, the Modify Parameters button is dimmed.
  3. In the Parameter Settings dialog box, click the Edit icon icon on the right of the parameter that you want to modify.
  4. Select or enter a new value in the Current Value column and click OK.
  5. In the Parameter Settings dialog box, check the new value and click OK.

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.