Amazon Aurora
User Guide for Aurora (API Version 2014-10-31)

Working with DB Parameter Groups and DB Cluster Parameter Groups

You manage your DB engine configuration by associating your DB instances and Aurora clusters with parameter groups. Amazon RDS defines parameter groups with default settings that apply to newly created DB instances and Aurora clusters. You can define your own parameter groups with customized settings. Then you can modify your DB instances and Aurora clusters to use your own parameter groups.

A DB parameter group acts as a container for engine configuration values that are applied to one or more DB instances. DB parameter groups apply to DB instances in both Amazon RDS and Aurora. These configuration settings apply to properties that can vary among the DB instances within an Aurora cluster, such as the sizes for memory buffers.

A DB cluster parameter group acts as a container for engine configuration values that are applied to every DB instance in an Aurora DB cluster. For example, the Aurora shared storage model requires that every DB instance in an Aurora cluster use the same setting for parameters such as innodb_file_per_table. Thus, parameters that affect the physical storage layout are part of the cluster parameter group. The DB cluster parameter group also includes default values for all the instance-level parameters

If you create a DB instance without specifying a DB parameter group, the DB instance uses a default DB parameter group. Likewise, if you create an Aurora DB cluster without specifying a DB cluster parameter group, the DB cluster uses a default DB cluster parameter group. Each default 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 or DB cluster 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. Likewise, if you update parameters within a DB cluster parameter group, the changes apply to all Aurora clusters that are associated with that DB cluster parameter group.

You can copy an existing DB parameter group with the AWS CLI copy-db-parameter-group command. You can copy an existing DB cluster parameter group with the AWS CLI copy-db-cluster-parameter-group command. Copying a parameter group can be convenient when you want to include most of an existing parameter group's custom parameters and values in a new parameter group.

Here are some important points about 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 takes effect after you manually reboot the DB instance. You can reboot a DB instance using the RDS console or by 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.

    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 new DB parameter group is used by the DB instance.

  • You can specify the value for a 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 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. Try out parameter group setting changes on a test DB instance before applying those parameter group changes to a production DB instance.

  • For an Aurora global database, you can specify different configuration settings for the individual Aurora clusters. Make sure that the settings are similar enough to produce consistent behavior if you promote a secondary cluster to be the primary cluster. For example, use the same settings for time zones and character sets across all the clusters of an Aurora global database.

Amazon Aurora DB Cluster and DB Instance Parameters

Aurora uses a two-level system of configuration settings, as follows:

  • Parameters in a DB cluster parameter group apply to every DB instance in a DB cluster. Your data is stored in the Aurora shared storage subsystem. Because of this, all parameters related to physical layout of table data must be the same for all DB instances in an Aurora cluster. Likewise, because Aurora DB instances are connected by replication, all the parameters for replication settings must be identical throughout an Aurora cluster.

  • Parameters in a DB parameter group apply to a single DB instance in an Aurora DB cluster. These parameters are related to aspects such as memory usage that you can vary across DB instances in the same Aurora cluster. For example, a cluster often contains DB instances with different AWS instance classes.

Every Aurora cluster is associated with a DB cluster parameter group. Each DB instance within the cluster inherits the settings from that DB cluster parameter group, and is associated with a DB parameter group. Aurora assigns default parameter groups when you create a cluster or a new DB instance, based on the specified database engine and version. You can change the parameter groups later to ones that you create, where you can edit the parameter values.

The DB cluster parameter groups also include default values for all the instance-level parameters from the DB parameter group. These defaults are mainly intended for configuring Aurora Serverless clusters, which are only associated with DB cluster parameter groups, not DB parameter groups. You can modify the instance-level parameter settings in the DB cluster parameter group. Then, Aurora applies those settings to each new DB instance that's added to a Serverless cluster. To learn more about configuration settings for Aurora Serverless clusters and which settings you can modify, see Aurora Serverless and Parameter Groups.

For non-Serverless clusters, any configuration values that you modify in the DB cluster parameter group override default values in the DB parameter group. If you edit the corresponding values in the DB parameter group, those values override the settings from the DB cluster parameter group.

Any DB parameter settings that you modify take precedence over the DB cluster parameter group values, even if you change the configuration parameters back to their default values. You can see which parameters are overridden by using the describe-db-parameters AWS CLI command or the DescribeDBParameters RDS API. The Source field contains the value user if you modified that parameter. To reset one or more parameters so that the value from the DB cluster parameter group takes precedence, use the reset-db-parameter-group AWS CLI command or the ResetDBParameterGroup RDS API operation.

The DB cluster and DB instance parameters available to you in Aurora vary depending on database engine compatibility.

Database Engine Parameters

Aurora MySQL

See Aurora MySQL Parameters.

For Aurora Serverless clusters, see additional details in Aurora Serverless and Parameter Groups.

Aurora PostgreSQL

See Amazon Aurora PostgreSQL Parameters.

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.

Console

To create a DB parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. Choose Create parameter group.

    The Create parameter group window appears.

  4. In the Parameter group family list, select a DB parameter group family.

  5. In the Type list, select DB Parameter Group.

  6. In the Group name box, enter the name of the new DB parameter group.

  7. In the Description box, enter a description for the new DB parameter group.

  8. Choose Create.

AWS CLI

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"

Note

The output contains duplicates.

Example

For Linux, OS X, or Unix:

aws rds create-db-parameter-group \ --db-parameter-group-name mydbparametergroup \ --db-parameter-group-family aurora5.6 \ --description "My new parameter group"

For Windows:

aws rds create-db-parameter-group ^ --db-parameter-group-name mydbparametergroup ^ --db-parameter-group-family aurora5.6 ^ --description "My new parameter group"

This command produces output similar to the following:

DBPARAMETERGROUP mydbparametergroup aurora5.6 My new parameter group
RDS API

To create a DB parameter group, use the RDS API CreateDBParameterGroup action.

Include the following required parameters:

  • DBParameterGroupName

  • DBParameterGroupFamily

  • Description

Creating a DB Cluster Parameter Group

You can create a new DB cluster parameter group using the AWS Management Console, the AWS CLI, or the RDS API.

Console

To create a DB cluster parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. Choose Create parameter group.

    The Create parameter group window appears.

  4. In the Parameter group family list, select a DB parameter group family

  5. In the Type list, select DB Cluster Parameter Group.

  6. In the Group name box, enter the name of the new DB cluster parameter group.

  7. In the Description box, enter a description for the new DB cluster parameter group.

  8. Choose Create.

CLI

To create a DB cluster parameter group, use the AWS CLI create-db-cluster-parameter-group command. The following example creates a DB cluster parameter group named mydbclusterparametergroup for MySQL version 5.6 with a description of "My new cluster parameter group."

Include the following required parameters:

  • --db-cluster-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"

Note

The output contains duplicates.

Example

For Linux, OS X, or Unix:

aws rds create-db-cluster-parameter-group \ --db-cluster-parameter-group-name mydbclusterparametergroup \ --db-parameter-group-family aurora5.6 \ --description "My new cluster parameter group"

For Windows:

aws rds create-db-cluster-parameter-group ^ --db-cluster-parameter-group-name mydbclusterparametergroup ^ --db-parameter-group-family aurora5.6 ^ --description "My new cluster parameter group"

This command produces output similar to the following:

DBCLUSTERPARAMETERGROUP mydbclusterparametergroup mysql5.6 My cluster new parameter group
RDS API

To create a DB cluster parameter group, use the RDS API CreateDBClusterParameterGroup action.

Include the following required parameters:

  • DBClusterParameterGroupName

  • DBParameterGroupFamily

  • Description

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.

If you change a parameter value, when the change is applied is determined by the type of parameter. Changes to dynamic parameters are applied immediately. Changes to static parameters require that the DB instance associated with DB parameter group be rebooted before the change takes effect. To determine the type of a parameter, list the parameters in a parameter group using one of the procedures shown in the section Listing DB Parameter Groups.

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.


				Parameter change pending reboot scenario
Console

To modify a DB parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. In the list, choose the parameter group that you want to modify.

  4. For Parameter group actions, choose Edit.

  5. 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.

  6. Choose Save changes.

CLI

To modify a DB parameter group, use the AWS CLI modify-db-parameter-group command with the following required parameters:

  • --db-parameter-group-name

  • --parameters

The following example modifies the max_connections and max_allowed_packet values in the DB parameter group named mydbparametergroup.

Note

Amazon RDS does not support passing multiple comma-delimited parameter values for a single parameter.

Example

For Linux, OS X, 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
RDS API

To modify a DB parameter group, use the RDS API ModifyDBParameterGroup command with the following required parameters:

  • DBParameterGroupName

  • Parameters

Modifying Parameters in a DB Cluster Parameter Group

You can modify parameter values in a customer-created DB cluster parameter group; you can't change the parameter values in a default DB cluster parameter group. Changes to parameters in a customer-created DB cluster parameter group are applied to all DB clusters that are associated with the DB cluster parameter group.

If you change a parameter value, when the change is applied is determined by the type of parameter. Changes to dynamic parameters are applied immediately. Changes to static parameters require that the DB instances associated with DB cluster that uses the DB cluster parameter group be rebooted before the change takes effect. To determine the type of a parameter, list the parameters in a parameter group using one of the procedures shown in the section Listing DB Parameter Groups.

The RDS console shows the status of the DB cluster parameter group associated with a DB instance. For example, if the DB instance is not using the latest changes to the associated DB cluster parameter group, the RDS console shows the DB cluster parameter group with a status of pending-reboot. You would need to manually reboot the DB instance for the latest parameter changes to take effect for that DB instance.


				Cluster parameter change pending reboot scenario
Console

To modify a DB cluster parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. In the list, choose the parameter group that you want to modify.

  4. For Parameter group actions, choose Edit.

  5. Change the values of the parameters 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.

  6. Choose Save changes.

CLI

To modify a DB cluster parameter group, use the AWS CLI modify-db-cluster-parameter-group command with the following required parameters:

  • --db-cluster-parameter-group-name

  • --parameters

The following example modifies the server_audit_logging and server_audit_logs_upload values in the DB cluster parameter group named mydbclusterparametergroup.

Note

Amazon RDS does not support passing multiple comma-delimited parameter values for a single parameter.

Example

For Linux, OS X, or Unix:

aws rds modify-db-cluster-parameter-group \ --db-cluster-parameter-group-name mydbclusterparametergroup \ --parameters "ParameterName=server_audit_logging,ParameterValue=1,ApplyMethod=immediate" \ "ParameterName=server_audit_logs_upload,ParameterValue=1,ApplyMethod=immediate"

For Windows:

aws rds modify-db-cluster-parameter-group ^ --db-cluster-parameter-group-name mydbclusterparametergroup ^ --parameters "ParameterName=server_audit_logging,ParameterValue=1,ApplyMethod=immediate" ^ "ParameterName=server_audit_logs_upload,ParameterValue=1,ApplyMethod=immediate"

The command produces output like the following:

DBCLUSTERPARAMETERGROUP mydbclusterparametergroup
RDS API

To modify a DB cluster parameter group, use the RDS API ModifyDBClusterParameterGroup command with the following required parameters:

  • DBClusterParameterGroupName

  • Parameters

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 CLI copy-db-parameter-group command or the RDS API CopyDBParameterGroup action.

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 or the describe-db-parameters command to verify that your DB parameter group is created.

Note

You can't copy a default parameter group. However, you can create a new parameter group that is based on a default parameter group.

Console

To copy a DB parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. In the list, choose the custom parameter group that you want to copy.

  4. For Parameter group actions, choose Copy.

  5. In New DB parameter group identifier, enter a name for the new parameter group.

  6. In Description, enter a description for the new parameter group.

  7. Choose Copy.

CLI

To copy a DB parameter group, use the AWS CLI copy-db-parameter-group command with the following required parameters:

  • --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, OS X, or Unix:

aws rds copy-db-parameter-group \ --source-db-parameter-group-identifier mygroup1 \ --target-db-parameter-group-identifier mygroup2 \ --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-identifier mygroup2 ^ --target-db-parameter-group-description "DB parameter group 2"
RDS API

To copy a DB parameter group, use the RDS API CopyDBParameterGroup action with the following required parameters:

  • SourceDBParameterGroupIdentifier

  • TargetDBParameterGroupIdentifier

  • TargetDBParameterGroupDescription

Copying a DB Cluster Parameter Group

You can copy custom DB cluster parameter groups that you create. Copying a parameter group is a convenient solution when you have already created a DB cluster parameter group and you want to include most of the custom parameters and values from that group in a new DB cluster parameter group. You can copy a DB cluster parameter group by using the AWS CLI copy-db-cluster-parameter-group command or the RDS API CopyDBClusterParameterGroup action.

After you copy a DB cluster parameter group, wait at least 5 minutes before creating your first DB cluster that uses that DB cluster parameter group as the default parameter group. Doing this allows Amazon RDS to fully complete the copy action before the parameter group is used as the default for a new DB cluster. You can use the Parameter Groups option of the Amazon RDS console or the describe-db-cluster-parameters command to verify that your DB cluster parameter group is created.

Note

You can't copy a default parameter group. However, you can create a new parameter group that is based on a default parameter group.

Console

To copy a DB cluster parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. In the list, choose the custom parameter group that you want to copy.

  4. For Parameter group actions, choose Copy.

  5. In New DB parameter group identifier, enter a name for the new parameter group.

  6. In Description, enter a description for the new parameter group.

  7. Choose Copy.

CLI

To copy a DB cluster parameter group, use the AWS CLI copy-db-cluster-parameter-group command with the following required parameters:

  • --source-db-cluster-parameter-group-identifier

  • --target-db-cluster-parameter-group-identifier

  • --target-db-cluster-parameter-group-description

The following example creates a new DB cluster parameter group named mygroup2 that is a copy of the DB cluster parameter group mygroup1.

Example

For Linux, OS X, or Unix:

aws rds copy-db-cluster-parameter-group \ --source-db-cluster-parameter-group-identifier mygroup1 \ --target-db-cluster-parameter-group-identifier mygroup2 \ --target-db-cluster-parameter-group-description "DB parameter group 2"

For Windows:

aws rds copy-db-cluster-parameter-group ^ --source-db-cluster-parameter-group-identifier mygroup1 ^ --target-db-cluster-parameter-group-identifier mygroup2 ^ --target-db-cluster-parameter-group-description "DB parameter group 2"
RDS API

To copy a DB cluster parameter group, use the RDS API CopyDBClusterParameterGroup action with the following required parameters:

  • SourceDBClusterParameterGroupIdentifier

  • TargetDBClusterParameterGroupIdentifier

  • TargetDBClusterParameterGroupDescription

Listing DB Parameter Groups

You can list the DB parameter groups you've created for your AWS account.

Note

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.

Console

To list all DB parameter groups for an AWS account

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

    The DB parameter groups appear in a list.

CLI

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, OS X, 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
RDS API

To list all DB parameter groups for an AWS account, use the RDS API DescribeDBParameterGroups action.

Listing DB Cluster Parameter Groups

You can list the DB cluster parameter groups you've created for your AWS account.

Note

Default parameter groups are automatically created from a default parameter template when you create a DB cluster 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.

Console

To list all DB cluster parameter groups for an AWS account

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

    The DB cluster parameter groups appear in the list with DB cluster parameter group for Type.

CLI

To list all DB cluster parameter groups for an AWS account, use the AWS CLI describe-db-cluster-parameter-groups command.

Example

The following example lists all available DB cluster parameter groups for an AWS account.

aws rds describe-db-cluster-parameter-groups

The command returns a response like the following:

DBCLUSTERPARAMETERGROUPS arn:aws:rds:us-west-2:1234567890:cluster-pg:default.aurora5.6 default.aurora5.6 aurora5.6 Default cluster parameter group for aurora5.6 DBCLUSTERPARAMETERGROUPS arn:aws:rds:us-west-2:1234567890:cluster-pg:mydbclusterparametergroup mydbclusterparametergroup aurora5.6 My new cluster parameter group

The following example describes the mydbclusterparametergroup parameter group.

For Linux, OS X, or Unix:

aws rds describe-db-cluster-parameter-groups \ --db-cluster-parameter-group-name mydbclusterparametergroup

For Windows:

aws rds describe-db-cluster-parameter-groups ^ --db-cluster-parameter-group-name mydbclusterparametergroup

The command returns a response like the following:

DBCLUSTERPARAMETERGROUPS arn:aws:rds:us-west-2:1234567890:cluster-pg:mydbclusterparametergroup mydbclusterparametergroup aurora5.6 My new cluster parameter group
RDS API

To list all DB cluster parameter groups for an AWS account, use the RDS API DescribeDBClusterParameterGroups action.

Viewing Parameter Values for a DB Parameter Group

You can get a list of all parameters in a DB parameter group and their values.

Console

To view the parameter values for a DB parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

    The DB parameter groups appear in a list.

  3. Choose the name of the parameter group to see its list of parameters.

CLI

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
RDS API

To view the parameter values for a DB parameter group, use the RDS API DescribeDBParameters command with the following required parameter.

  • DBParameterGroupName

Viewing Parameter Values for a DB Cluster Parameter Group

You can get a list of all parameters in a DB cluster parameter group and their values.

Console

To view the parameter values for a DB cluster parameter group

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

    The DB cluster parameter groups appear in the list with DB cluster parameter group for Type.

  3. Choose the name of the DB cluster parameter group to see its list of parameters.

CLI

To view the parameter values for a DB cluster parameter group, use the AWS CLI describe-db-cluster-parameters command with the following required parameter.

  • --db-cluster-parameter-group-name

Example

The following example lists the parameters and parameter values for a DB cluster parameter group named mydbclusterparametergroup.

aws rds describe-db-cluster-parameters --db-cluster-parameter-group-name mydbclusterparametergroup

The command returns a response like the following:

PARAMETERS pending-reboot dynamic string IAM role ARN used to load data from AWS S3 True aurora_load_from_s3_role engine-default PARAMETERS pending-reboot dynamic string IAM role ARN used to select data into AWS S3 True aurora_select_into_s3_role engine-default PARAMETERS pending-reboot dynamic string Default IAM role ARN used to access AWS Lambda Service True aws_default_lambda_role engine-default PARAMETERS pending-reboot dynamic string Arn for the role used to upload data to CloudWatch Logs True aws_default_logs_role engine-default
RDS API

To view the parameter values for a DB cluster parameter group, use the RDS API DescribeDBClusterParameters command with the following required parameter.

  • DBClusterParameterGroupName

Comparing 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

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Parameter groups.

  3. In the list, choose the two parameter groups that you want to compare.

  4. For Parameter group actions, choose Compare.

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}

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.

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.

Note

DB Parameter functions are not currently supported in the AWS CLI.

IF()

Returns an argument.

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.

Warning

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 LEAST() function in an Aurora MySQL table_definition_cache parameter value to set the number of table definitions that can be stored in the definition cache to the lesser of DBInstanceClassMemory/393040 or 20,000.

LEAST({DBInstanceClassMemory/393040}, 20000)