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What Is a Parameter Group?

DB parameter groups act as a container for engine configuration values that are applied to one or more DB instances. You can customize the parameter settings to manage DB engine configurations.

Type

When creating a DB instance, you can associate a default parameter group or a customized parameter group with the DB instance. After a DB instance is created, you can also change the associated parameter group.

  • Default parameter groups

    The DB engine parameter values and system service parameter values in the default parameter group are designed for optimizing the database performance.

  • Custom parameter groups

    If you need a DB instance with customized parameter settings, you can create a parameter group and change the parameter values as required.

    If you change the parameter values of the parameter group associated with several DB instances, the changes will apply to all these DB instances.

Application Scenarios

  • If you want to use a customized parameter group, you only need to create a parameter group in advance and select the parameter group when creating a DB instance. For details about how to create a parameter group, see Creating a Parameter Group.
  • If you need to change the associated parameter group, see Changing Associated Parameter Group.
  • When you have already created a parameter group and want to include most of the custom parameters and values from that group in a new parameter group, you can replicate that parameter group following the instructions provided in section Replicating a Parameter Group.

Precautions

  • Default parameter groups are unchangeable. You can only view them by clicking their names. If inappropriate settings of customized parameter groups lead to a database startup failure, you can reset the customized parameter group by referring to the settings of the default parameter group.
  • After modifying a parameter, you need to view the associated instance status in the instance list. If Pending restart is displayed, you need to restart the instance for the modification to take effect.
  • Improperly setting parameters in a parameter group may have unintended adverse effects, including degraded performance and system instability. Exercise caution when modifying database parameters and you need to back up data before modifying parameters in a parameter group. Before applying parameter changes to a production DB instance, you should try out these changes on a test DB instance.
Parent topic: Parameter Group Settings