Create and manage parameter groups

In parameter groups, you can view and manage the parameters required for PostgreSQL settings all at once, according to the engine version.
Additionally, you can collectively manage the parameters of instance groups linked to the corresponding parameter group.

The parameters and basic concepts provided by KakaoCloud PostgreSQL follow the official documentation of PostgreSQL. Since changing parameters may affect the PostgreSQL service, it is recommended to verify the appropriate parameter values to be entered in advance.

The following explains how to manage parameter groups in the PostgreSQL service.

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• You can receive notifications for events related to parameter groups, such as creation and modification, through the Alert Center > Event notification feature. For the list of configurable events, check the Cloud Trail > Key concepts guide, and for setting up event notifications, refer to the Alert Center > Create and manage notification policies guide.
• For instance groups created before November 27, 2025, when the parameter group feature was added, the 'predeploy' parameter group is linked. The parameter values within the group may differ from the values retrieved directly from MySQL. Also, when changing a parameter group, PostgreSQL will restart for the first time to apply the parameters.

View parameter group list

You can check the list of parameter groups (default/custom) provided by KakaoCloud PostgreSQL.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select either the Custom group or Default group tab according to the category you want to check.
3. Move to the Parameter Group menu corresponding to the selected tab.

Item	Description
Name	Name of the parameter group
Engine version	PostgreSQL engine version compatible with the parameter group
Number of linked instance groups	Number of instance groups connected to this group - A warning icon appears if there is an issue with the parameter application status of a linked instance group.
Description	Description of the parameter group
More	Provided for custom groups only - Edit: Edit parameters - Copy: Create a new parameter group with the same parameters as this group - Reset to default values: Reset the parameters of this group to their initial values at the time of creation - Rollback: Revert the parameters of this group to the previous values; rollback is not possible if there are no modifications or if a rollback has already been performed - Delete: Delete this group

View parameter group details

You can check the detailed information of a PostgreSQL parameter group.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select either the Custom group or Default group tab.
3. Select the parameter group you want to view details for.

Tab: Parameters

Item	Description
Name	Name of the parameter
Value	Value of the parameter
Unit	Unit of the parameter
Type	Parameter type: Static, Dynamic - Static parameters require a restart to be applied - Some Dynamic parameters are applied globally and require session renewal
Data type	Data format of the parameter
Editable	No, Yes, Yes (Modified) - Values can only be modified if it is Yes. If modified, it is displayed as Yes (Modified)

Tab: Linked instance groups

Item	Description
Name	Name of the instance group
Status	Status of the instance group
Parameter application status	Application status of the parameters. For more details, refer to Parameter application status
Engine version	PostgreSQL engine version of the instance group
Instance type	Instance type used for the instance group configuration
Availability	Instance availability: Single, High Availability
[Button] Retry	Retry applying parameters to the instance group when the status is Error-Sync or Suspended

Tab: Recent events

You can check major events for the parameter group that occurred within the last 7 days.

Item	Description
Time	Time when the event occurred
Event name	Name of the event
Details	Check event details, results, and the name of the instance group where the event occurred

• Parameter group recent event types:

Parameter group type	Event name	Description
Custom parameter group	Create Parameter Group	Occurs when a custom parameter group is created
	Update Parameter Group	Occurs when information (description) of a custom parameter group is modified
	Update Parameter	Occurs when a parameter value is modified
	Reset Parameters	Occurs when a request is made to reset parameter values to their initial values
	Rollback Parameters	Occurs when a request is made to roll back parameter values
	Apply Instance Group	Occurs when applying the parameter group to an instance group is completed
Default parameter group	Apply Instance Group	Occurs when applying the parameter group to an instance group is completed

Create parameter group

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Click the icon > Create parameter group.
4. Enter the required information on the Create parameter group page. Parameter values can be modified after the group is created.

Item	Category	Description
Basic settings	Parameter group name	Name of the parameter group - Duplicate names within the same project cannot be used
	Description (Optional)	Add a description up to 100 characters
Parameter group settings	Engine version	PostgreSQL engine version for the parameter group
	Default parameter group	Select the default parameter group provided for that engine version
Parameters		Initial parameter values for the group

Modify parameter group

For custom parameter groups, you can change the description and parameter values after creation. Only parameters with an editable status of Yes can be modified. Modified parameters will be labeled as Yes (Modified).

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• Some Dynamic parameters are applied globally and require session renewal.
• If Static parameters are modified, linked instance groups will be restarted.
• Parameters cannot be modified if the application status of linked instance groups is Pending or Applying.
• In the edit page, selected checkboxes are maintained even if you navigate through the list of editable parameters.

caution

• Modifying certain parameters may affect PostgreSQL service operations. For more details, check Parameters to be careful of when modifying.
• If problems occur after modification, it is recommended to use the Copy feature for backup, or use Retry/Rollback/Reset.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Click the [More] icon for the group to be modified and select Edit.
4. Modify the content on the Modify parameter group page.

Item	Category	Description
Basic information	Parameter group name	Name of the parameter group
	Description (Optional)	Add a description up to 100 characters
Editable parameters		List of editable parameters - Modified parameters change to Yes (Modified)

5. You can manually enter values, use the Import existing parameters feature to load values from another custom group, or use the Reset to default values feature. After editing, click the [OK] button.
6. If multiple instance groups are linked, you can choose the application method:
   Bulk application: Applies modifications to all instance groups at once.
   Sequential application: Applies modifications to instance groups one after another.

Import existing parameters

You can load parameter values from an existing custom parameter group regardless of the version. Loading values will replace existing entries, so it is recommended to save any necessary information beforehand.

1. Go to the Modify parameter group page.
2. In the Import existing parameters popup, select the engine version and the target custom parameter group.
3. Check the values and click the [Apply] button.

caution

When modifying values in a custom parameter group, certain parameters can impact PostgreSQL service operations. Please refer to Parameters to be careful of when modifying.

Use expressions, functions, and keywords in parameters

Some parameters in custom parameter groups support keywords. These can only be used for numeric and string type parameters.
The result of a calculation must be a number within the range of int64 (-9,223,372,036,854,775,807 to 9,223,372,036,854,775,807).

Expressions and functions

Category	Description
Expression	Must always be written inside {}
	(), +, -, *, / are supported
	The result must always be a number
	If the data type is INTEGER, decimal points are discarded
Function	MAX(a, b, ...): Returns the largest value (Uppercase only)
	MIN(a, b, ...): Returns the smallest value (Uppercase only)
	SUM(a, b, ...): Returns the sum of values (Uppercase only)
	IF(condition, a, b): Returns a if true, b if false (Uppercase only)

Keywords

Size-related keywords kc.InstanceMemory, kc.VolumeSizeData, kc.VolumeSizeLog are based on GB units.
Since the calculation units in expressions are based on the unit of each parameter, calculations must be adjusted accordingly.

Category	Keyword	Description
Keyword	kc.InstanceMemory	Memory size of the current DB instance type (GB)
	kc.InstanceMemoryMB	Memory size converted to MB ex. kc.InstanceMemoryMB = kc.InstanceMemory * 1024
	kc.InstanceMemoryKB	Memory size converted to KB ex. kc.InstanceMemoryKB = kc.InstanceMemory * 1024 * 1024
	kc.VolumeSizeData	Data volume size (GB)
	kc.VolumeSizeDataMB	Data volume size converted to MB
	kc.VolumeSizeDataKB	Data volume size converted to KB
	kc.VolumeSizeLog	Log volume size (GB)
	kc.VolumeSizeLogMB	Log volume size converted to MB
	kc.VolumeSizeLogKB	Log volume size converted to KB

Expression examples for units

1. shared_buffers parameter calculation
# Since keywords are in GB, they must be converted to 8KB units
{((kc.InstanceMemory * 1024 * 1024 / 8)-((kc.InstanceMemory * 1024 * 1024 / 8) * 0.4))* 0.7} / unit: 8kb / dataType: integer

2. work_mem parameter calculation
# '100' is calculated as 100KB based on the unit.
{kc.InstanceMemory * 1024 * 1024 + 100} / unit: kb / dataType: integer (memory: 8GB)

3. maintenance_work_mem parameter calculation
{MAX(kc.InstanceMemory * 1024 * 1024 * 0.015, 65536)} / unit: kb / dataType: integer

Copy parameter group

Custom parameter groups provide a copy feature, which can be used for backup purposes. You can create a new parameter group by copying an existing one.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to copy, click the [More] icon, and select Copy.
4. Review the input information in the Copy parameter group popup and click the [OK] button.
5. Verify the copied parameter group in the Custom group tab.

Reset parameter group to default values

Custom parameter groups offer a feature to reset modified parameter values back to their initial defaults. Initial values refer to the default settings provided by the specific engine version selected when the parameter group was created. Resetting to default values will attempt to apply the changes to all linked instance groups simultaneously.

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• You cannot reset to default values if no parameters have been modified after the custom parameter group was created, or if the parameter application status of linked instance groups is Pending or Applying.
• If Static parameters are reset, the linked instance groups will be restarted.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to reset, click the [More] icon, and select Reset parameters to default values.
4. Review the guidance in the Reset parameters to default values popup and click the [OK] button.
   If multiple instance groups are linked to the parameter group, you can choose the application method:
   Bulk application: Applies the modified parameters to all instance groups at once.
   Sequential application: Applies the modified parameters to instance groups one after another.
5. If there are linked instance groups, verify that the reset has been successfully applied by checking the parameter application status of each instance group.

Roll back parameter group

Custom parameter groups provide a rollback feature that allows you to revert parameter values to their state immediately preceding the most recent modification. This feature is only available if there is a record of a recent modification.

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• You cannot roll back a parameter group if the parameter application status of linked instance groups is Pending or Applying.
• If Static parameters are rolled back, the linked instance groups will be restarted.
• Once a rollback is performed, you cannot roll back further to an even earlier modification history, as the current state has already reverted to the immediately preceding one. If you modify parameters again after a rollback, a new modification history is created, making the rollback feature available once more.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to roll back, click the [More] icon, and select Rollback.
4. Review the guidance in the Rollback parameter group popup and click the [OK] button.
5. If there are linked instance groups, verify that the rollback has been successfully applied by checking the parameter application status of each instance group.

Delete parameter group

You can delete a custom parameter group if it is no longer in use.

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• Default parameter groups cannot be deleted.
• A parameter group cannot be deleted if there are any linked instance groups.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to delete, click the [More] icon, and select Delete.
4. Fill in the required information in the Delete parameter group popup and click the [OK] button.
5. Verify that the parameter group has been removed from the Custom group tab.

Retry parameter group application

You can retry applying parameters only when the application status of a linked instance is Error-Sync or Suspended, rather than In-Sync.
For a detailed explanation of application statuses, please refer to the Parameter application status guide.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Navigate to the appropriate Parameter Group menu and select the group you wish to view in detail.
4. Go to the Linked Instance Group tab.
5. Click the [Retry] button for the instance you wish to retry.

Verify parameter group engine version

If the engine version of an instance group linked to a parameter group does not match (e.g., due to a version upgrade), a Verify engine version badge will be displayed.
By clicking the Parameter Group menu and selecting the Instance tab, you can identify which instance groups have mismatched engine versions. The badge will disappear once you change the parameter group to one with a matching engine version using the Change parameter group feature.

Custom parameter groups displaying this badge cannot be modified to ensure service stability. If the Verify engine version badge is visible, you must identify the mismatched instance group and change it to an appropriate parameter group that matches the engine version.
If you want to use a parameter group with previously configured values, it is recommended to create a new parameter group with the correct version and then use the Import existing parameters feature within Modify parameter group.