Manage instance groups

caution

Periodic monitoring and management are recommended to ensure that log storage usage does not exceed 80%.
In KakaoCloud's Alert Center, you can set notification policies based on disk usage and usage rates.
The PostgreSQL details screen provides guidance on expanding storage through the Expand volume feature once usage reaches 85% or higher.
If storage usage exceeds an appropriate level of 90% or more, archive logs will be deleted in order from oldest to newest to ensure service stability.

Create PostgreSQL instance group

A PostgreSQL instance group manages the lifecycle of instances and backups. It has various status values including running and terminated states, which can be viewed and managed by users.

To create an instance group in the PostgreSQL service:

info

• If instance group creation fails due to unexpected causes such as network errors or lack of resources, check the logs in Cloud Trail.
  
• Even if you expand volumes after creating an instance group, the maximum IOPS is fixed at the initially specified value. To ensure stable performance, set an appropriate volume size at creation.

1. Go to the KakaoCloud console > Data Store > PostgreSQL.

2. Select the [Create instance group] button.

3. Fill in the required information and select [Create].

   Item	Category	Description
   Basic settings	Instance group name	Name of the PostgreSQL instance group - Must be unique within the same project - Example: PostgreSQL-instance-01
   	Description (optional)	Optional description up to 100 characters
   Instance availability	High availability (Primary + Standby)	Creates a primary instance and multiple standby instances - Supports single or multi-AZ
   	Single (Primary only)	Creates only one primary instance - Single AZ only
   PostgreSQL settings	Engine version	Automatically selected version of PostgreSQL - Currently provides version 14.14, 14.17
   	Primary port	Port for communication with primary instance (1024–65535) - Default: 5432
   	Standby port	Port for communication with standby instance (required for HA) - Default: 5433
   	ID	PostgreSQL database user account ID - Example: admin * Reserved IDs such as root, postgres, rewind, replication, orafce_set_umask, plprofiler are not allowed
   	Password	Initial password for the PostgreSQL database user - Format: 8–16 characters - Cannot include space, /, ', ", @ ⚠️ Password can be changed after database startup ⚠️ Passwords changed after startup cannot be retrieved
   Parameter group		You can select a parameter group that matches the selected engine version
   Instance type		Select the instance type for computing resources - See Instance types for details
   Base storage	SSD	Configure volume type and size - Type: Only SSD currently supported - Size: 100 GB–16,384 GB * Minimum size may vary depending on instance type
   Log storage	SSD	Storage for database logs. Cannot be changed after creation. - Type: Only SSD supported - Size: 100 GB–16,384 GB * Minimum size may vary depending on instance type
   Network settings	Multi-AZ option	Option available when HA is selected. Set subnets and number of instances per AZ
   	VPC	Select the network (VPC) for PostgreSQL instances
   	Subnet and instance count	Specify subnets for primary and standby instances and the number of instances - Up to 6 instances per group - At least 2 standby instances are recommended for redundancy
   	Security group	Create or select security groups to apply - Multiple selections allowed

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For more on instance groups, see Instance group.

User accounts in instance groups

When creating a PostgreSQL instance group, the user can specify a custom ID and password to generate a database user account.
This account has Admin privileges and can access resources after authentication. The roles and privileges are as follows:

info

• Accounts with reserved IDs (root, postgres, replication, rewind, orafce_set_umask, plprofiler) cannot be created.
• If the replication account is deleted, HA mode may fail to function properly.

Type	Privileges
User account	Create role, Create DB, Bypass RLS, Password valid until infinity

Connect to PostgreSQL instance group

To connect an instance to a PostgreSQL instance group, use PostgreSQL Client after the group and instance are created.

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In case of automatic or manual failover, or restarts, the primary instance may change, resulting in momentary connection disruption due to changes in internal endpoint mappings.

Prerequisites

To connect to a PostgreSQL instance group, ensure a VM instance exists within the same network and that the endpoint of the PostgreSQL group is accessible.
Allow custom ports (1024–65535) or default PostgreSQL ports (Primary: 5432, Standby: 5433) in the associated security group.

Connect instance

You can now connect to the PostgreSQL instance.

1. Refer to Virtual Machine > Create and connect to instance to set up a VM and install PostgreSQL Client if not already available.

2. Go to the KakaoCloud console > Data Store > PostgreSQL.

3. From the Instance Group menu, select the instance group to connect.

4. In the Details tab, copy the Endpoint and User ID.

5. From the VM, use the following PostgreSQL connection commands:

   PostgreSQL connection method 1

   $ PGPASSWORD={USER_PASSWORD} psql -h {ENDPOINT} -U {USER_ID} -d {DATABASE} -p {PORT}

   PostgreSQL connection method 2

   $ psql postgres://{USER_ID}:{USER_PASSWORD}@{ENDPOINT}:{PORT}/{DATABASE}

   Item	Description
   {USER_ID}	DB administrator account ID used to connect
   {USER_PASSWORD}	Password for the above user ID (set during creation)
   {ENDPOINT}	Endpoint retrieved from Details tab
   {DATABASE}	Name of the database to connect to - Default is postgres unless user created another database
   {PORT}	Port configured during instance group creation - Default: Primary 5432, Standby 5433

Manage instance groups

Describes how to manage active PostgreSQL instances and groups.

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When the instance group status is Storage-Full (a state where Log or Data disk usage for instances in the PostgreSQL instance group is 85% or higher, or available capacity is 30 GB or less) or the instance status is Storage-Error (a state where an instance's Log or Data disk usage is 95% or higher, or available capacity remains at 10 GB or less for more than 5 minutes), only volume expansion can be performed to ensure service stability.

View instance group list

You can view a list of currently running PostgreSQL instance groups.

1. Go to the KakaoCloud console > Data Store > PostgreSQL.

2. View the list from the Instance group menu.

   Item	Description
   Instance group name	Name entered at creation - Select to view details
   Status	Instance group status - See Instance group for details
   Engine version	PostgreSQL version selected during creation
   Instance type	Type selected during creation
   Availability	Availability mode selected
   Multi-AZ	Whether multi-AZ is enabled
   Created at	Date and time of creation
   Created by	User who first created the instance
   [⋮] button	Set automatic backup: Configure automatic backup settings, usage status, retention period, and backup start time for the instance group. Expand volume: Expand the volumes (Data, Log storage) of the PostgreSQL instance group. Change parameter group: Change the parameter group applied to the instance group. Manual failover: Proceed with a failover for the instance group (Available only in High Availability). Create backup: Create a backup for the instance group. Delete: Return the instance resources included in the PostgreSQL instance group and delete the backups.

View instance group details

You can view details for a PostgreSQL instance group.

1. Go to the KakaoCloud console > Data Store > PostgreSQL.
2. From the Instance Group menu, select the desired group.
3. View the detailed information of that group.

Expand instance group volumes

You can expand volumes up to 16TB (16,384 GB) for both base and log storage.

info

Volume expansion only increases disk space. Maximum IOPS does not increase. IOPS scaling based on size will be supported in the future.

1. Go to the KakaoCloud console > Data Store > PostgreSQL.
2. From the Instance Group menu, select [More options] > Expand volume.
3. Enter the new size for base or log storage and select [OK].

Delete instance group

You can delete PostgreSQL instance groups that are no longer needed.
All instances will be shut down and released. Billing stops once the group is deleted.

caution

Once deleted, all instance resources and backups in the PostgreSQL instance group are permanently removed and cannot be recovered.

1. Go to the KakaoCloud console > Data Store > PostgreSQL.
2. From the Instance Group menu, select [More options] > Delete for the target group.
3. Fill in the required information in the Delete popup and select [Delete].

Change parameter group

You can change the parameter group associated with an instance group.
When changing, you must select a parameter group that matches the engine version of the instance group. Note that changing parameter values may affect the PostgreSQL service currently in operation. Therefore, it is recommended to verify the parameter values to be applied before making any changes.

If a parameter group change is already in progress, additional change requests may fail. For more information, please refer to the Parameter group guide.

1. In the KakaoCloud Console, go to the Data Store > PostgreSQL menu.
2. In the Instance Group menu, click the [More] icon for the instance group you want to modify and select Change parameter group.
3. In the Change parameter group popup, select the parameter group you want to change to and click the [OK] button.