Create and manage parameter group

In a parameter group, you can view and manage MySQL configuration parameters based on the engine version.
Additionally, you can collectively manage the parameters of instance groups linked to the parameter group.

The list of parameters and basic concepts provided by KakaoCloud MySQL follow MySQL's official documentation. Changing parameters can impact MySQL service, so it is recommended to refer to the official documentation to confirm appropriate values in advance.

Here is how to manage parameter groups in MySQL service.

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• Events such as creation and modification of parameter groups can be received via Alert Center > Event notifications.
  
• For configurable event types, refer to Cloud Trail > Overview, and for event notification settings, refer to the Alert Center > Create and manage notification policy guide.

View parameter group list

You can check the list of default and custom parameter groups provided by KakaoCloud MySQL.

1. Go to KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu, then select the Custom group or Default group tab depending on the type of parameter group you want to view.
3. The Parameter Group menu will change depending on the selected tab.

Item	Description
Name	Name of the parameter group
Engine version	MySQL engine version compatible with the parameter group
Linked instance group count	Number of instance groups linked to the parameter group - If there is an issue applying parameters to the linked instance group, a warning icon is displayed
Description	Description of the parameter group
More	Available only for custom groups - Edit: Modify parameters - Copy: Create a new parameter group with the same parameters - Reset to default: Revert parameters to the initial values set during creation - Rollback: Revert parameter values to the previous ones (not possible if no edit history or rollback already performed) - Delete: Delete the group

View parameter group details

You can view detailed information about MySQL parameter groups.

1. Go to KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group or Default group tab.
3. Navigate to the Parameter Group menu for the selected tab, then select the parameter group whose details you want to view.

Tab: Parameters

Item	Description
Name	Name of the parameter
Value	Value of the parameter
Type	Type of parameter: Static, Dynamic - Static parameters require a restart to apply - Some Dynamic parameters require session refresh due to global application
Data type	Data type of the parameter
Editable	Not allowed, Allowed, Allowed (modified) - Only Allowed parameters can be modified, and will be shown as Allowed (modified) once changed

Tab: Linked instance group

Item	Description
Name	Name of the instance group
Status	Status of the instance group
Parameter application status	Status of parameter application. See Parameter application status for details
Engine version	MySQL engine version of the instance group
Instance type	Instance type used for configuring the instance group
Availability	Instance availability: Single, High availability
[Button] Retry	Retry parameter application when status is Error-Sync or Suspended

Tab: Recent events

You can view major parameter group events from the past 7 days.

Item	Description
Time	Time the event occurred
Name	Event name
Description	Description of the event, including results and associated instance group

• Recent event types by parameter group

Parameter group type	Event name	Description
Custom parameter group	Create Parameter Group	Triggered when a custom parameter group is created
	Update Parameter Group	Triggered when the custom group's info (e.g. description) is modified
	Update Parameter	Triggered when parameter values are modified
	Reset Parameters	Triggered when a reset to default is requested
	Rollback Parameters	Triggered when a rollback is requested
	Apply Instance Group	Triggered when the group is successfully applied to an instance group
Default parameter group	Apply Instance Group	Triggered when the group is successfully applied to an instance group

Create parameter group

1. Go to the KakaoCloud Console > Data Store > MySQL menu.

2. Click the Parameter Group menu and select the Custom group tab according to the parameter group classification.

3. In the Custom group tab, click the icon > [Create parameter group].

4. On the Create parameter group page, fill in the required details. Parameter values can be modified after creating the group.

   Item	Category	Description
   Basic settings	Parameter group name	Name of the parameter group - Duplicate names cannot be used within the same project
   	Description (optional)	Additional description for the parameter group, up to 100 characters
   Parameter group settings	Engine version	MySQL engine version for the parameter group
   	Default parameter group	Select the default parameter group provided for the selected engine version
   Parameters		Initial parameter values for the parameter group

Modify parameter group

You can modify the description and values of parameters in a custom parameter group after it is created. Only parameters with modifiable status can be edited. Once edited, their status changes to modifiable (edited).

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• Some parameters of type Dynamic apply globally and require a session refresh.
• If parameters of type Static are modified, the connected instance group will be restarted.
• If the parameter application status of the connected instance group is Pending or Applying, the parameters cannot be modified.
• When navigating through the editable parameter list, selected checkboxes remain checked.

caution

• Some parameters may impact MySQL service operations if modified. For details, see Parameters to be careful when modifying.
• If problems occur after modifying parameters, it is recommended to first [Copy] the parameter group for backup, and then perform Retry, Rollback, or Reset.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.

2. Click the Parameter Group menu and select the Custom group tab.

3. Select the parameter group to be modified and click the [More] icon > [Edit].

4. On the Edit parameter group page, modify the necessary information.

   Item	Category	Description
   Basic information	Parameter group name	Name of the parameter group
   	Description (optional)	Additional description for the parameter group, up to 100 characters
   Editable parameters		List of parameters that can be edited in the parameter group - Edited parameters will show as modifiable (edited)

5. If the parameter group is connected to multiple instance groups, choose how to apply the changes.
   Apply all at once: Apply the modified parameters to all instance groups at once.
   Apply sequentially: Apply the modified parameters to instance groups in sequence.

Parameters to be careful when modifying

Some parameters in a custom parameter group may affect MySQL service operation when modified. Please review the details below.

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If inappropriate values are set for collation or character set parameters, service issues may occur. Refer to the official documentation for guidance: Charset combinations, Charset-collation compatibility.

Parameter name	Description	Potential issues
innodb_ft_aux_table	Auxiliary table for InnoDB full-text search	Incorrect setting may cause full-text search failure - Must specify an existing table Unknown behavior if non-existent table is used
innodb_buffer_pool_size	Size of the InnoDB buffer pool	Too small: performance degradation Too large: memory shortage - Buffer pool memory is adjusted as a multiple of {innodb_buffer_chunk_size * innodb_buffer_pool_instances} * Example: {kc.InstanceMemory * 7 / 10}
innodb_log_file_size	Size of each InnoDB log file	Too small: performance degradation Too large: longer recovery time
innodb_buffer_pool_chunk_size	Chunk size used when allocating InnoDB buffer pool	Too small: inefficient memory allocation Too large: longer initialization time - Must be a multiple of innodb_buffer_pool_size - Automatically increases innodb_buffer_pool_size when changed * Example: { (kc.InstanceMemory * 7 / 10) / (kc.InstanceVcpu * 2) }
innodb_buffer_pool_instances	Number of instances to split the InnoDB buffer pool	Too low: contention and performance degradation Too high: memory waste * Fixed value: 134217728
innodb_redo_log_capacity	Total capacity of InnoDB redo log	Too small: performance degradation Too large: increased disk usage * Example: { MIN(kc.InstanceMemory * 7 / 10 / 4, 2147483648) }
max_connections	Maximum number of concurrent MySQL connections	Too low: users may not connect Too high: excessive resource use * Example: { MIN(kc.InstanceMemory / 12582880, 16000) }
time_zone	Time zone of MySQL server	Incorrect setting may cause timestamp/data issues Client time zones will be reset * Example: `system
collation_connection collation_server	Defines collation rules for charset in databases/tables/columns	Incorrect settings may cause data integrity issues, performance loss, or incompatibility Settings should align with related character set parameters Official documentation
character_set_client character_set_connection character_set_filesystem character_set_results character_set_server	Specifies charset used in databases, tables, columns Affects how string data is stored/processed Inappropriate settings can cause data corruption, performance issues, or incompatibility Settings should align with collation parameters Official documentation

Use expressions, functions, and keywords in parameters

Some parameters in custom parameter groups support expressions, functions, and reserved keywords. These can only be used with numeric or string parameters.
The result must be a number within the int64 range (-9,223,372,036,854,775,807 to 9,223,372,036,854,775,807).
See details below:

Category	Description
Expressions	Enclosed in {}
	Support: (), +, -, *, /
	Result must always be a number
	Decimal parts are discarded if data type is INTEGER
Functions	MAX(a, b, ...): Returns the largest value
	MIN(a, b, ...): Returns the smallest value
	SUM(a, b, ...): Returns the sum of values
	IF(condition, a, b): Returns a if true, b if false
Reserved keywords	kc.InstanceMemory: Memory size of current DB instance in bytes
	kc.InstanceVcpu: Number of virtual CPU cores
	kc.VolumeSizeData: Data volume size
	kc.VolumeSizeLog: Log volume size
	kc.InstanceCount: Total number of nodes
	kc.InstancePrimaryCount: Number of primary nodes
	kc.InstanceStandbyCount: Number of standby nodes
	kc.InstanceGroupId: Instance group ID

Example usage

Example of calculating the default value for max_connections:

{ MIN(kc.InstanceMemory / 12582880, 16000) }

Copy parameter group

Custom parameter groups support a copy feature that can be used for backup. You can copy a selected parameter group to create a new one.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to copy, then click the [More] icon > [Copy].
4. In the Copy parameter group popup, review the input information and click the [Confirm] button.
5. Verify that the copied parameter group appears in the Custom group tab.

Reset parameter group to default values

Custom parameter groups support resetting parameters back to their default values. The default values refer to the initial values provided by the engine version selected when creating the parameter group. When reset to default, parameter changes are applied to all connected instance groups at once.

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• You cannot reset parameters if the parameter application status of the connected instance group is Pending or Applying.
• When a parameter of type Static is reset, the connected instance group will be restarted.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to reset, then click the [More] icon > [Reset to default values].
4. In the Reset to default values popup, review the guide and click the [Confirm] button.
   If the parameter group is connected to multiple instance groups, select the parameter application method.
   Apply all at once: Apply parameters to all instance groups simultaneously.
   Apply sequentially: Apply parameters to instance groups one by one.
5. If there are connected instance groups, check their parameter application status to confirm the reset was applied properly.

Roll back parameter group

Custom parameter groups provide a rollback feature that allows reverting to the most recently modified values. This feature is only available if the parameter group was modified just before the rollback attempt.

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• You cannot roll back parameters if the parameter application status of the connected instance group is Pending or Applying.
• When a parameter of type Static is rolled back, the connected instance group will be restarted.
• Once rolled back, you cannot revert to values modified prior to the last change. However, if you modify parameters again, rollback becomes available for the latest change.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to roll back, then click the [More] icon > [Roll back].
4. In the Roll back parameter group popup, review the guide and click the [Confirm] button.
5. If there are connected instance groups, check their parameter application status to confirm the rollback was applied properly.

Delete parameter group

If a custom parameter group is no longer needed, it can be deleted.

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• Default parameter groups cannot be deleted.
• If the parameter group is connected to any instance group, it cannot be deleted.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Identify the parameter group to delete, then click the [More] icon > [Delete].
4. In the Delete parameter group popup, fill in the required information and click the [Confirm] button.
5. Verify that the parameter group has been deleted from the Custom group tab.

Retry parameter group application

Retrying parameter application is only possible if the application status of a connected instance is not In-Sync but Error-Sync or Suspended.
For detailed information on parameter application status, see Parameter application status.

1. Go to the KakaoCloud Console > Data Store > MySQL menu.
2. Click the Parameter Group menu and select the Custom group tab.
3. Go to the appropriate Parameter Group tab and select the parameter group you want to inspect.
4. Go to the Connected instance group tab.
5. For the instance where you want to retry, click the [Retry] button.