Aurora MySQL working with parameters in a parameter group

When you change a dynamic parameter and save the parameter group, the change is applied immediately regardless of the Apply Immediately setting. When you change a static parameter and save the DB parameter group, the parameter change will take effect after you manually reboot the DB instance. You can reboot a DB instance using the RDS console or explicitly calling the RebootDbInstance API action (without failover, if the DB instance is in a Multi-AZ deployment). The requirement to reboot the associated DB instance after a static parameter change helps mitigate the risk of a parameter misconfiguration affecting an API call, such as calling ModifyDBInstance to change DB instance class or scale storage.

When you change the DB parameter group associated with a DB instance, you must manually reboot the instance before the new DB parameter group is used by the DB instance.

The value for a parameter can be specified as an integer or as an integer expression built from formulas, variables, functions, and operators. Functions can include a mathematical log expression. For more information, see DB Parameter Values.

Set any parameters that relate to the character set or collation of your database in your parameter group prior to creating the DB instance and before you create a database in your DB instance. This ensures that the default database and new databases in your DB instance use the character set and collation values that you specify. If you change character set or collation parameters for your DB instance, the parameter changes are not applied to existing databases.

You can change character set or collation values for an existing database using the ALTER DATABASE command, for example:


ALTER DATABASE database_name CHARACTER SET character_set_name COLLATE collation;

Improperly setting parameters in a parameter group can have unintended adverse effects, including degraded performance and system instability. Always exercise caution when modifying database parameters and back up your data before modifying a parameter group. You should try out parameter group setting changes on a test DB instance before applying those parameter group changes to a production DB instance.