Working with DB parameter groups
You manage your DB engine configuration by associating your DB instances with parameter groups. Amazon RDS defines parameter groups with default settings that apply to newly created DB instances.
You can define your own parameter groups with customized settings. Then you can modify your DB instances to use your own parameter groups.
For information about modifying a DB instance, see Modifying an Amazon RDS DB instance.
A DB parameter group acts as a container for engine configuration values that are applied to one or more DB instances.
If you create a DB instance without specifying a DB parameter group, the DB instance uses a default DB parameter group. Each default DB parameter group contains database engine defaults and Amazon RDS system defaults based on the engine, compute class, and allocated storage of the instance. You can't modify the parameter settings of a default parameter group. Instead, you create your own parameter group where you choose your own parameter settings. Not all DB engine parameters can be changed in a parameter group that you create.
If you want to use your own parameter group, you create a new parameter group and modify the parameters that you want to. You then modify your DB instance to use the new parameter group. If you update parameters within a DB parameter group, the changes apply to all DB instances that are associated with that parameter group.
You can copy an existing DB parameter group with the AWS CLI copy-db-parameter-group command. Copying a parameter group can be convenient when you want to include most of an existing DB parameter group's custom parameters and values in a new DB parameter group.
Here are some important points about working with parameters in a DB parameter group:
-
When you change a dynamic parameter and save the DB 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 takes effect after you manually reboot the DB instance. You can reboot a DB instance using the RDS console, by calling the
reboot-db-instance
CLI command, or by calling theRebootDbInstance
API operation. 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 callingModifyDBInstance
to change DB instance class or scale storage.If a DB instance isn't using the latest changes to its associated DB parameter group, the AWS Management Console shows the DB parameter group with a status of pending-reboot. The pending-reboot parameter groups status doesn't result in an automatic reboot during the next maintenance window. To apply the latest parameter changes to that DB instance, manually reboot the DB instance.
-
When you change the DB parameter group associated with a DB instance, you must manually reboot the instance before the DB instance can use the new DB parameter group. For more information about changing the DB parameter group, see Modifying an Amazon RDS DB instance.
-
You can specify the value for a DB parameter 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 before 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 SETcharacter_set_name
COLLATEcollation
; -
Improperly setting parameters in a DB 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 DB parameter group. Try out parameter group setting changes on a test DB instance before applying those parameter group changes to a production DB instance.
-
To determine the supported parameters for your DB engine, you can view the parameters in the DB parameter group used by the DB instance. For more information, see Viewing parameter values for a DB parameter group.
Topics
- Creating a DB parameter group
- Associating a DB parameter group with a DB instance
- Modifying parameters in a DB parameter group
- Resetting parameters in a DB parameter group to their default values
- Copying a DB parameter group
- Listing DB parameter groups
- Viewing parameter values for a DB parameter group
- Comparing DB parameter groups
- DB parameter values
Creating a DB parameter group
You can create a new DB parameter group using the AWS Management Console, the AWS CLI, or the RDS API.
To create a DB parameter group
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
-
Choose Create parameter group.
The Create parameter group window appears.
-
In the Parameter group family list, select a DB parameter group family.
-
In the Type list, select DB Parameter Group.
-
In the Group name box, enter the name of the new DB parameter group.
-
In the Description box, enter a description for the new DB parameter group.
-
Choose Create.
To create a DB parameter group, use the AWS CLI create-db-parameter-group
command. The following
example creates a DB parameter group named mydbparametergroup
for MySQL version 5.6 with a description of "My new parameter
group."
Include the following required parameters:
-
--db-parameter-group-name
-
--db-parameter-group-family
-
--description
To list all of the available parameter group families, use the following command:
aws rds describe-db-engine-versions --query "DBEngineVersions[].DBParameterGroupFamily"
The output contains duplicates.
Example
For Linux, macOS, or Unix:
aws rds create-db-parameter-group \ --db-parameter-group-name
mydbparametergroup
\ --db-parameter-group-familyMySQL5.6
\ --description"My new parameter group"
For Windows:
aws rds create-db-parameter-group ^ --db-parameter-group-name
mydbparametergroup
^ --db-parameter-group-familyMySQL5.6
^ --description"My new parameter group"
This command produces output similar to the following:
DBPARAMETERGROUP mydbparametergroup mysql5.6 My new parameter group
To create a DB parameter group, use the RDS API CreateDBParameterGroup
operation.
Include the following required parameters:
-
DBParameterGroupName
-
DBParameterGroupFamily
-
Description
Associating a DB parameter group with a DB instance
You can create your own DB parameter groups with customized settings. You can associate a DB parameter group with a DB instance using the AWS Management Console, the AWS CLI, or the RDS API. You can do so when you create or modify a DB instance.
For information about creating a DB parameter group, see Creating a DB parameter group. For information about creating a DB instance, see Creating an Amazon RDS DB instance. For information about modifying a DB instance, see Modifying an Amazon RDS DB instance.
When you change the DB parameter group associated with a DB instance, you must manually reboot the instance before the DB instance can use the new DB parameter group.
To associate a DB parameter group with a DB instance
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Databases, and then choose the DB instance that you want to modify.
-
Choose Modify. The Modify DB Instance page appears.
-
Change the DB parameter group setting.
-
Choose Continue and check the summary of modifications.
-
(Optional) Choose Apply immediately to apply the changes immediately. Choosing this option can cause an outage in some cases. For more information, see Using the Apply Immediately setting.
-
On the confirmation page, review your changes. If they are correct, choose Modify DB instance to save your changes.
Or choose Back to edit your changes or Cancel to cancel your changes.
To associate a DB parameter group with a DB instance, use the AWS CLI
modify-db-instance
command with the following options:
-
--db-instance-identifier
-
--db-parameter-group-name
The following example associates the mydbpg
DB parameter group with the
database-1
DB instance. The changes are applied immediately by using --apply-immediately
.
Use --no-apply-immediately
to apply the changes during the next maintenance window.
For more information, see
Using the Apply Immediately setting.
Example
For Linux, macOS, or Unix:
aws rds modify-db-instance \ --db-instance-identifier
database-1
\ --db-parameter-group-namemydbpg
\--apply-immediately
For Windows:
aws rds modify-db-instance ^ --db-instance-identifier
database-1
^ --db-parameter-group-namemydbpg
^--apply-immediately
To associate a DB parameter group with a DB instance, use the RDS API
ModifyDBInstance
operation with the following parameters:
-
DBInstanceName
-
DBParameterGroupName
Modifying parameters in a DB parameter group
You can modify parameter values in a customer-created DB parameter group; you can't change the parameter values in a default DB parameter group. Changes to parameters in a customer-created DB parameter group are applied to all DB instances that are associated with the DB parameter group.
Changes to some parameters are applied to the DB instance immediately without a reboot. Changes to other parameters are applied only after the DB instance is rebooted. The RDS console shows the status of the DB parameter group associated with a DB instance on the Configuration tab. For example, if the DB instance isn't using the latest changes to its associated DB parameter group, the RDS console shows the DB parameter group with a status of pending-reboot. To apply the latest parameter changes to that DB instance, manually reboot the DB instance.

To modify a DB parameter group
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
-
In the list, choose the parameter group that you want to modify.
-
For Parameter group actions, choose Edit.
-
Change the values of the parameters that you want to modify. You can scroll through the parameters using the arrow keys at the top right of the dialog box.
You can't change values in a default parameter group.
-
Choose Save changes.
To modify a DB parameter group, use the AWS CLI modify-db-parameter-group
command with the following
required options:
-
--db-parameter-group-name
-
--parameters
The following example modifies the max_connections
and
max_allowed_packet
values in the DB parameter group named
mydbparametergroup.
Example
For Linux, macOS, or Unix:
aws rds modify-db-parameter-group \ --db-parameter-group-name
mydbparametergroup
\ --parameters "ParameterName=max_connections
,ParameterValue=250
,ApplyMethod=immediate
" \ "ParameterName=max_allowed_packet
,ParameterValue=1024
,ApplyMethod=immediate
"
For Windows:
aws rds modify-db-parameter-group ^ --db-parameter-group-name
mydbparametergroup
^ --parameters "ParameterName=max_connections
,ParameterValue=250
,ApplyMethod=immediate
" ^ "ParameterName=max_allowed_packet
,ParameterValue=1024
,ApplyMethod=immediate
"
The command produces output like the following:
DBPARAMETERGROUP mydbparametergroup
To modify a DB parameter group, use the RDS API
ModifyDBParameterGroup
operation with the following required parameters:
-
DBParameterGroupName
-
Parameters
Resetting parameters in a DB parameter group to their default values
You can reset parameter values in a customer-created DB parameter group to their default values. Changes to parameters in a customer-created DB parameter group are applied to all DB instances that are associated with the DB parameter group.
When you use the console, you can reset specific parameters to their default values, but you can't easily reset all of the parameters in the DB parameter group at once. When you use the AWS CLI or RDS API, you can reset specific parameters to their default values, and you can reset all of the parameters in the DB parameter group at once.
Changes to some parameters are applied to the DB instance immediately without a reboot. Changes to other parameters are applied only after the DB instance is rebooted. The RDS console shows the status of the DB parameter group associated with a DB instance on the Configuration tab. For example, if the DB instance isn't using the latest changes to its associated DB parameter group, the RDS console shows the DB parameter group with a status of pending-reboot. To apply the latest parameter changes to that DB instance, manually reboot the DB instance.

In a default DB parameter group, parameters are always set to their default values.
To reset parameters in a DB parameter group to their default values
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
-
In the list, choose the parameter group.
-
For Parameter group actions, choose Edit.
-
Choose the parameters that you want to reset to their default values. You can scroll through the parameters using the arrow keys at the top right of the dialog box.
You can't reset values in a default parameter group.
-
Choose Reset and then confirm by choosing Reset parameters.
To reset some or all of the parameters in a DB parameter group, use the AWS CLI
reset-db-parameter-group
command with the following
required option: --db-parameter-group-name
.
To reset all of the parameters in the DB parameter group, specify the --reset-all-parameters
option.
To reset specific parameters, specify the --parameters
option.
The following example resets all of the parameters in the DB parameter group named mydbparametergroup to their default values.
Example
For Linux, macOS, or Unix:
aws rds reset-db-parameter-group \ --db-parameter-group-name
mydbparametergroup
\ --reset-all-parameters
For Windows:
aws rds reset-db-parameter-group ^ --db-parameter-group-name
mydbparametergroup
^ --reset-all-parameters
The following example resets the max_connections
and
max_allowed_packet
options to their default values in the DB parameter group named
mydbparametergroup.
Example
For Linux, macOS, or Unix:
aws rds reset-db-parameter-group \ --db-parameter-group-name
mydbparametergroup
\ --parameters "ParameterName=max_connections
,ApplyMethod=immediate
" \ "ParameterName=max_allowed_packet
,ApplyMethod=immediate
"
For Windows:
aws rds reset-db-parameter-group ^ --db-parameter-group-name
mydbparametergroup
^ --parameters "ParameterName=max_connections
,ApplyMethod=immediate
" ^ "ParameterName=max_allowed_packet
,ApplyMethod=immediate
"
The command produces output like the following:
DBParameterGroupName mydbparametergroup
To reset parameters in a DB parameter group to their default values, use the RDS API
ResetDBParameterGroup
command with the following
required parameter: DBParameterGroupName
.
To reset all of the parameters in the DB parameter group, set the ResetAllParameters
parameter to true
.
To reset specific parameters, specify the Parameters
parameter.
Copying a DB parameter group
You can copy custom DB parameter groups that you create. Copying a parameter group is a convenient solution when you have already created a DB parameter group and you want to include most of the custom parameters and values from that group in a new DB parameter group. You can copy a DB parameter group by using the AWS Management Console, the AWS CLI copy-db-parameter-group command, or the RDS API CopyDBParameterGroup operation.
After you copy a DB parameter group, wait at least 5 minutes before creating your
first DB instance
that uses that DB parameter group as the default parameter group. Doing this allows
Amazon RDS to fully complete
the copy action before the parameter group is used. This is especially important for
parameters that are
critical when creating the default database for a DB instance. An example is the character
set for the
default database defined by the character_set_database
parameter. Use the Parameter
Groups option of the Amazon RDS console
You can't copy a default parameter group. However, you can create a new parameter group that is based on a default parameter group.
Currently, you can't copy a parameter group to a different AWS Region.
To copy a DB parameter group
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
-
In the list, choose the custom parameter group that you want to copy.
-
For Parameter group actions, choose Copy.
-
In New DB parameter group identifier, enter a name for the new parameter group.
-
In Description, enter a description for the new parameter group.
-
Choose Copy.
To copy a DB parameter group, use the AWS CLI
copy-db-parameter-group
command with the following required options:
-
--source-db-parameter-group-identifier
-
--target-db-parameter-group-identifier
-
--target-db-parameter-group-description
The following example creates a new DB parameter group named mygroup2
that is a copy of the DB parameter group mygroup1
.
Example
For Linux, macOS, or Unix:
aws rds copy-db-parameter-group \ --source-db-parameter-group-identifier
mygroup1
\ --target-db-parameter-group-identifiermygroup2
\ --target-db-parameter-group-description"DB parameter group 2"
For Windows:
aws rds copy-db-parameter-group ^ --source-db-parameter-group-identifier
mygroup1
^ --target-db-parameter-group-identifiermygroup2
^ --target-db-parameter-group-description"DB parameter group 2"
To copy a DB parameter group, use the RDS API CopyDBParameterGroup
operation with the following required parameters:
-
SourceDBParameterGroupIdentifier
-
TargetDBParameterGroupIdentifier
-
TargetDBParameterGroupDescription
Listing DB parameter groups
You can list the DB parameter groups you've created for your AWS account.
Default parameter groups are automatically created from a default parameter template when you create a DB instance for a particular DB engine and version. These default parameter groups contain preferred parameter settings and can't be modified. When you create a custom parameter group, you can modify parameter settings.
To list all DB parameter groups for an AWS account
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
The DB parameter groups appear in a list.
To list all DB parameter groups for an AWS account, use the AWS CLI describe-db-parameter-groups
command.
Example
The following example lists all available DB parameter groups for an AWS account.
aws rds describe-db-parameter-groups
The command returns a response like the following:
DBPARAMETERGROUP default.mysql5.5 mysql5.5 Default parameter group for MySQL5.5 DBPARAMETERGROUP default.mysql5.6 mysql5.6 Default parameter group for MySQL5.6 DBPARAMETERGROUP mydbparametergroup mysql5.6 My new parameter group
The following example describes the mydbparamgroup1 parameter group.
For Linux, macOS, or Unix:
aws rds describe-db-parameter-groups \ --db-parameter-group-name
mydbparamgroup1
For Windows:
aws rds describe-db-parameter-groups ^ --db-parameter-group-name
mydbparamgroup1
The command returns a response like the following:
DBPARAMETERGROUP mydbparametergroup1 mysql5.5 My new parameter group
To list all DB parameter groups for an AWS account, use the RDS API DescribeDBParameterGroups
operation.
Viewing parameter values for a DB parameter group
You can get a list of all parameters in a DB parameter group and their values.
To view the parameter values for a DB parameter group
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
The DB parameter groups appear in a list.
-
Choose the name of the parameter group to see its list of parameters.
To view the parameter values for a DB parameter group, use the AWS CLI describe-db-parameters
command with the following
required parameter.
-
--db-parameter-group-name
Example
The following example lists the parameters and parameter values for a DB parameter group named mydbparametergroup.
aws rds describe-db-parameters --db-parameter-group-name
mydbparametergroup
The command returns a response like the following:
DBPARAMETER Parameter Name Parameter Value Source Data Type Apply Type Is Modifiable DBPARAMETER allow-suspicious-udfs engine-default boolean static false DBPARAMETER auto_increment_increment engine-default integer dynamic true DBPARAMETER auto_increment_offset engine-default integer dynamic true DBPARAMETER binlog_cache_size 32768 system integer dynamic true DBPARAMETER socket /tmp/mysql.sock system string static false
To view the parameter values for a DB parameter group, use the RDS API DescribeDBParameters
command with the following
required parameter.
-
DBParameterGroupName
Comparing DB parameter groups
You can use the AWS Management Console to view the differences between two parameter groups for the same DB engine and version.
To compare two parameter groups
-
Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/
. -
In the navigation pane, choose Parameter groups.
-
In the list, choose the two parameter groups that you want to compare.
-
For Parameter group actions, choose Compare.
Note If the items you selected aren't equivalent, you can't choose Compare. For example, you can't compare a MySQL 5.6 and a MySQL 5.7 parameter group. You can't compare a DB parameter group and an Aurora DB cluster parameter group.
DB parameter values
You can specify the value for a DB parameter as any of the following:
-
An integer constant
-
A DB parameter formula
-
A DB parameter function
-
A character string constant
-
A log expression (the log function represents log base 2), such as
value={log(DBInstanceClassMemory/8187281418)*1000}
Currently, you can't specify the MySQL innodb_log_file_size
parameter with
any value other than an integer.
DB parameter formulas
A DB parameter formula is an expression that resolves to an integer value or a Boolean value, and is enclosed in braces: {}. You can specify formulas for either a DB parameter value or as an argument to a DB parameter function.
Syntax
{FormulaVariable} {FormulaVariable*Integer} {FormulaVariable*Integer/Integer} {FormulaVariable/Integer}
DB parameter formula variables
Each formula variable returns integer or a Boolean value. The names of the variables are case-sensitive.
- AllocatedStorage
-
Returns the size, in bytes, of the data volume.
- DBInstanceClassMemory
-
Returns the number of bytes of memory allocated to the DB instance class associated with the current DB instance, less the memory used by the Amazon RDS processes that manage the instance.
- EndPointPort
-
Returns the number of the port used when connecting to the DB instance.
- DBInstanceClassHugePagesDefault
-
Returns a Boolean value. Currently, it is only supported for Oracle engines.
For more information, see Using HugePages with an Oracle DB instance.
DB parameter formula operators
DB parameter formulas support two operators: division and multiplication.
- Division Operator: /
-
Divides the dividend by the divisor, returning an integer quotient. Decimals in the quotient are truncated, not rounded.
Syntax
dividend / divisor
The dividend and divisor arguments must be integer expressions.
- Multiplication Operator: *
-
Multiplies the expressions, returning the product of the expressions. Decimals in the expressions are truncated, not rounded.
Syntax
expression * expression
Both expressions must be integers.
DB parameter functions
The parameter arguments can be specified as either integers or formulas. Each function must have at least one argument. Multiple arguments can be specified as a comma-separated list. The list can't have any empty members, such as argument1,,argument3. Function names are case-insensitive.
- IF()
-
Returns an argument.
Currently, it is only supported for Oracle engines, and the only supported first argument is
{DBInstanceClassHugePagesDefault}
. For more information, see Using HugePages with an Oracle DB instance.Syntax
IF(argument1, argument2, argument3)
Returns the second argument if the first argument evaluates to true. Returns the third argument otherwise.
- GREATEST()
-
Returns the largest value from a list of integers or parameter formulas.
Syntax
GREATEST(argument1, argument2,...argumentn)
Returns an integer.
- LEAST()
-
Returns the smallest value from a list of integers or parameter formulas.
Syntax
LEAST(argument1, argument2,...argumentn)
Returns an integer.
- SUM()
-
Adds the values of the specified integers or parameter formulas.
Syntax
SUM(argument1, argument2,...argumentn)
Returns an integer.
DB parameter value examples
These examples show using formulas and functions in the values for DB parameters.
Improperly setting parameters in a DB 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 your DB parameter group. Try out parameter group changes on a test DB instances, created using point-in-time-restores, before applying those parameter group changes to your production DB instances.
You can specify the GREATEST
function in an Oracle
processes parameter to set the number of user processes to the larger of either
80
or DBInstanceClassMemory
divided by 9,868,951.
GREATEST({DBInstanceClassMemory/9868951},80)
You can specify the LEAST()
function in a MySQL
max_binlog_cache_size
parameter value to set the maximum cache size
a transaction can use in a MySQL instance to the lesser of 1 MB or
DBInstanceClass
/256.
LEAST({DBInstanceClassMemory/256},10485760)