Key Concepts
The key concepts of the PostgreSQL service are as follows:
| Key Concept | Description |
|---|---|
| Instance group | An object that manages the lifecycle of instances and backups. |
| Instance | A VM managed by an instance group, with roles determined as Primary or Standby based on availability. |
| Instance type | Virtualized hardware resources, including vCPU and memory, for database usage. - Supports various types optimized for different workloads. |
| Instance lifecycle | Enables monitoring and managing the operational and task status of instance groups and instances through their lifecycle. |
| Backup | Managed online without database downtime, including creation and deletion of backups. |
| Volume | Provides databases using block storage devices without requiring users to create or configure block storage directly. |
| Network and security | Offers networking and security features in VPCs, allowing for logically isolated service environments based on network requirements. |
| IAM and security | Grants appropriate access permissions via IAM and ensures secure management of PostgreSQL resources. |
Instance group
Instance groups are objects that manage the lifecycle of instances and backups.
PostgreSQL instance groups have various statuses, including operational and terminated, enabling users to monitor and manage instance groups.
Instance group lifecycle and status values
When creating a PostgreSQL instance group, it begins in the Pending state, transitions through Provisioning and Primary Available states, and finally reaches the Available state. Instance groups in the Available state can be accessed via endpoint and port configurations within the selected network. Default ports are 5432 for Primary and 5433 for Standby, with user-defined ports available between 1024–65535 during creation.
Instance group lifecycle
PostgreSQL instance group lifecycle
| Status | Description |
|---|---|
Pending | Preparing to configure the instance group. - Initial state upon instance group creation. |
Provisioning | Creating and configuring necessary resources for the instance group. |
Primary Available | High-availability mode with one or more standby instances partially configured. Primary remains available, but Standby is unavailable. |
Switching | A standby instance is being promoted to primary due to issues with the current primary. - Triggered by manual/automatic failover. |
Available | All instances in the instance group are in Running state and fully operational.Accessible via network endpoint. |
Terminating | Deleting all instances and associated resources, including backups. |
Terminated | All resources in the instance group have been deleted. |
Error | Temporary issue causing partial inaccessibility of the instance group. |
Fatal | Irrecoverable error during configuration, preventing the instance group from reaching a stable state. |
Instance
Instances are VMs managed by instance groups.
PostgreSQL instances include virtualized databases with CPU and memory resources. They exist as objects within PostgreSQL instance groups and can function as Primary or Standby, based on their availability.
Instance roles
| Role | Description |
|---|---|
| Primary | The main instance for read and write operations. - Accessible via the endpoint. |
| Standby | High-availability instance for failover and read-only operations. - Created when high availability is selected. |
Instance types
PostgreSQL services offer a variety of instance types optimized for different workloads.
Instance specifications are determined by the type selected during instance group creation. Usage-based charges apply.
m2a (General Purpose) and r2a (Memory-Optimized) Types
| Instance Type | vCPU (cores) | Memory (GiB) |
|---|---|---|
| m2a.large | 2 | 8 |
| m2a.xlarge | 4 | 16 |
| m2a.2xlarge | 8 | 32 |
| m2a.4xlarge | 16 | 64 |
| m2a.8xlarge | 32 | 128 |
| r2a.large | 2 | 16 |
| r2a.xlarge | 4 | 32 |
| r2a.2xlarge | 8 | 64 |
| r2a.4xlarge | 16 | 128 |
| r2a.8xlarge | 32 | 256 |
Instance lifecycle and status values
Instances begin in the Pending state and transition through Provisioning and Starting to reach the Running state.
PostgreSQL instance lifecycle
PostgreSQL instance lifecycle
| Status | Description |
|---|---|
Pending | Initial state while preparing to configure the instance. |
Starting | Resources are being created to configure the instance. |
Restarting | Instance is restarting due to a user request. |
Warning | Instance communication is possible, but some features are limited. |
Running | Instance is operational, with PostgreSQL service running normally. |
Volume-Extending | Instance's volume is being extended. |
Terminating | Instance is being terminated, with all resources deleted. |
Terminated | Instance and its resources have been fully terminated. |
Error | Instance has encountered an error, making it temporarily unavailable. |
Fatal | Irrecoverable error occurred during instance creation. |
Instance availability and roles
The number of instances and their roles are determined based on the instance availability configuration.
| Instance Availability Configuration | Number of Created Instances | Description |
|---|---|---|
| Single (Single, Primary Instance) | 1 | Creates only one primary instance |
| High Availability (HA, Primary, Standby Instances) | Up to 6 | Creates primary and standby instances - 1 primary and 1 to 5 standby instances |
Instance availability status
Represents the status of data replication between PostgreSQL instances. This applies only to instance groups with high availability selected.
PostgreSQL Instance Availability Status
| Availability Status | Description |
|---|---|
Configuring | Status where the data replication setup for PostgreSQL instances is in progress |
Configured | Status where data replication for PostgreSQL instances is functioning normally |
Unavailable | Status where data replication for PostgreSQL instances has stopped |
Backup
Backups are managed at the instance group level.
Backup lifecycle and status values
Backups start in the Pending state, transition through Processing, and complete in the Available state.
Backup Status
PostgreSQL backup lifecycle
| Status | Description |
|---|---|
Pending | Initial state before resources for the backup are created. |
Processing | Backup is being created. |
Available | Backup has been successfully completed and is ready for restoration. |
Restoring | Backup is being used for restoration and cannot be deleted. |
Deleting | Backup is being deleted. |
Deleted | Backup has been fully deleted. |
Error | Backup failed, and valid backup information is unavailable. |
Fatal | Irrecoverable error occurred during backup creation, leaving the object nonexistent. |
Failover
PostgreSQL supports High Availability (HA) with auto-failover and manual failover options.
Failover promotes one of the standby instances to primary when a failure occurs.
Failover may cause brief service disruptions.
Failover lifecycle
| Status | Description |
|---|---|
SWITCHING | Failover is in progress. PostgreSQL service is temporarily unavailable. |
PRIMARY-AVAILABLE | Standby instances are being configured. |
Volume
PostgreSQL uses block storage volumes to provide databases. Users do not need to create or manage block storage directly.
Network and security
All PostgreSQL instances are hosted in VPC environments.
VPCs provide network and security features, enabling logically isolated service environments tailored to network requirements. For more details, refer to VPC documentation.