Step 2: Buy a DB Instance

Scenarios

This section describes how to buy a DB instance on the RDS console.

RDS for PostgreSQL supports the yearly/monthly and pay-per-use billing modes. RDS allows you to tailor your compute resources and storage space to your business needs.

Prerequisites

You have registered a Huawei ID and enabled Huawei Cloud services.

Procedure

Go to the Buy DB Instance page.

On that page, click the Custom Config tab, select a billing mode, and configure information about your DB instance. Then, click Buy.

Billing Mode
- Yearly/Monthly: If you select this mode, skip 3 and go to 4.
- Pay-per-use: If you select this mode, go to 3.

Engine Options

Figure 1 Billing mode and basic information

**Table 1** Basic information
Parameter	Description
Region	Region where your resources are located. NOTE: Products in different regions cannot communicate with each other through a private network. After a DB instance is created, the region cannot be changed. Therefore, exercise caution when selecting a region.
DB Engine	Set to PostgreSQL.
DB Engine Version	For details, see DB Engines and Versions. Different DB engine versions are supported in different regions. You are advised to select the latest available version because it is more stable, reliable, and secure.
DB Instance Type	Primary/Standby: uses an HA architecture with a primary DB instance and a synchronous standby DB instance. It is suitable for production databases of large and medium enterprises in Internet, Internet of Things (IoT), retail e-commerce sales, logistics, gaming, and other sectors. The standby DB instance improves instance reliability and is invisible to you after being created. An AZ is a physical region where resources use independent power supply and networks. AZs are physically isolated but interconnected through an internal network. Some regions support both single AZs and multiple AZs and some only support single AZs. To achieve high reliability, RDS will automatically deploy your primary and standby instances in different physical servers even if you deploy them in the same AZ. If you attempt to create primary/standby DB instances in the same AZ in a Dedicated Computing Cluster (DCC) and there is only one physical server available, the creation will fail. You can deploy primary and standby DB instances in a single AZ or across AZs to achieve failover and high availability. Single: uses a single-node architecture, which is less expensive than primary/standby DB instances. It is suitable for development and testing of microsites, and small- and medium-sized enterprises, or for learning about RDS.
Storage Type	Determines the DB instance read/write speed. The higher the maximum throughput is, the higher the DB instance read/write speed can be. Ultra-high I/O: supports a maximum throughput of 350 MB/s. Cloud SSD: cloud disks used to decouple storage from compute. Extreme SSD: uses 25GE network and RDMA technologies to provide you with up to 1,000 MB/s throughput per disk and sub-millisecond latency. NOTE: The cloud SSD and extreme SSD storage types are supported with general-purpose, dedicated, and Kunpeng general-enhanced DB instances. If you have purchased the Dedicated Distributed Storage Service (DSS), only the storage type that you have selected when you buy the DSS service is displayed. The IOPS supported by cloud SSDs depends on the I/O performance of Elastic Volume Service (EVS) disks. For details, see the description about ultra-high I/O in Disk Types and Performance of Elastic Volume Service Service Overview. The IOPS supported by extreme SSDs depends on the I/O performance of Elastic Volume Service (EVS) disks. For details, see the description about extreme SSDs in Disk Types and Performance of Elastic Volume Service Service Overview.

Instance Configuration

Figure 2 DB instance specifications

**Table 2** Instance specifications
Parameter	Description
Instance Class	Refers to the vCPU and memory of a DB instance. Different instance classes support different numbers of database connections and maximum IOPS. After a DB instance is created, you can change its vCPU and memory. For details, see Changing a DB Instance Class. NOTE: Only general-enhanced DB instances are allowed for a DCC.
Resource Type	EVS DSS NOTE: This option is displayed only when you have purchased Dedicated Distributed Storage Service (DSS).
Storage Pool	Displayed only when you select DSS for Resource Type. The storage pool is secure because it is physically isolated from other pools.
Storage Space (GB)	Contains the system overhead required for inodes, reserved blocks, and database operation. Storage space can range in size from 40 GB to 4,000 GB and can be scaled up only by a multiple of 10 GB. If the storage type is cloud SSD or extreme SSD, you can enable storage autoscaling. If the available storage drops to a specified threshold, autoscaling is triggered. If you specify a read replica when creating a primary DB instance and enable storage autoscaling for the primary DB instance, storage autoscaling is also enabled for the read replica by default. Enable autoscaling: If you select this option, autoscaling is enabled. Trigger If Available Storage Drops To: If the available storage drops to a specified threshold or 10 GB, autoscaling is triggered. Autoscaling Limit: The default value range is from 40 GB to 4,000 GB. The limit must be no less than the storage of the DB instance. After a DB instance is created, you can scale up its storage space. For details, see Scaling up Storage Space.
Disk Encryption	Disable: indicates the encryption function is disabled. Enable: indicates the encryption function is enabled, improving data security but affecting system performance. Key Name: indicates the tenant key. Select one from the drop-down list. To create a key, click Create Key and configure parameters in the displayed dialog box. For more information, see Creating a Key in the Data Encryption Workshop User Guide. NOTE: If you enable disk encryption during instance creation, the disk encryption status and the key cannot be changed later. Disk encryption will also encrypt backup data stored in OBS. If disk encryption is enabled, keep the key properly. Once the key is disabled, deleted, or frozen, the database will be unavailable and data may not be restored. If a shared KMS key is used, the corresponding CTS events are createdatakey and decrydatakey. Only the key owner can receive the events.

Basic Settings and Connectivity

Figure 3 Basic settings and connectivity

**Table 3** Network
Parameter	Description
DB Instance Name	The instance name must start with a letter and consist of 4 to 64 characters. Only letters (case-sensitive), digits, hyphens (-), and underscores (_) are allowed. If you intend to buy multiple DB instances at a time, the allowed length for each instance name will change. If you buy multiple instances at a time, a hyphen (-) followed by a number with four digits will be appended to the instance name, starting with -0001. For example, if you enter instance, the first instance will be named instance-0001, the second instance-0002, and so on.
Password	Configure (default setting): Configure a password for your DB instance during the creation process. Skip: Configure a password later after the DB instance is created. NOTICE: If you select Skip for Password, you need to reset the password before you can log in to the instance. After a DB instance is created, you can reset the password. For details, see Resetting the Administrator Password.
Administrator	The default login name for the database is root.
Administrator Password	Must consist of 8 to 32 characters and contain at least three types of the following characters: uppercase letters, lowercase letters, digits, and special characters (~ ! @ # $ % ^ * - _ = + ? ,). Enter a strong password and periodically change it for security reasons. If the password you provide is regarded as a weak password by the system, you will be prompted to enter a stronger password. Keep this password secure. The system cannot retrieve it. After a DB instance is created, you can reset this password. For details, see Resetting the Administrator Password.
Confirm Password	Must be the same as Administrator Password.
VPC	A virtual network in which your RDS DB instances are located. A VPC can isolate networks for different workloads. You can select an existing VPC or create a VPC. For details on how to create a VPC, see the "Creating a VPC" section in the Virtual Private Cloud User Guide. If no VPC is available, RDS allocates a VPC to you by default. To use a shared VPC, select a VPC that another account shares with the current account from the drop-down list. VPC owners can share the subnets in a VPC with one or multiple accounts through Resource Access Manager (RAM). Through VPC sharing, you can easily configure, operate, and manage multiple accounts' resources at low costs. For more information about VPC and subnet sharing, see VPC Sharing. NOTICE: After a DB instance is created, the VPC cannot be changed.
Subnet	Improves network security by providing dedicated network resources that are logically isolated from other networks. Subnets take effect only within an AZ. The Dynamic Host Configuration Protocol (DHCP) function is enabled by default for subnets in which you plan to create RDS DB instances and cannot be disabled. IPv4 address: A floating IPv4 address is automatically assigned when you create a DB instance. You can also enter an unused floating IPv4 address in the subnet CIDR block. After the DB instance is created, you can change the floating IP address. IPv6 address: A DB instance assigned a floating IPv6 address will be created only when the vCPUs and memory you selected support IPv6 addresses. A floating IPv6 address is automatically assigned during instance creation and cannot be specified. After the DB instance is created, this floating IP address cannot be changed.
Security Group	Controls the access that traffic has in and out of a DB instance. By default, the security group associated with the DB instance is authorized. In addition, a network access control list (ACL) can help control inbound and outbound traffic of subnets in your VPC. Enhances security by controlling access to RDS from other services. You need to add inbound rules to a security group so that you can connect to your DB instance. When creating a DB instance, you can select multiple security groups. For better network performance, you are advised to select no more than five security groups. In such a case, the access rules of all the selected security groups apply on the instance. To use multiple security groups, choose Service Tickets > Create Service Ticket in the upper right corner of the management console to apply for the required permissions. If no security group is available, RDS allocates a security group to you by default.

Additional Options

Figure 4 Additional options

**Table 4** Additional options
Parameter	Description
Enterprise Project	If your account has been associated with an enterprise project, select the target project from the Enterprise Project drop-down list. For more information about enterprise projects, see Enterprise Management User Guide.
Parameter Template	Contains engine configuration values that can be applied to one or more DB instances. If you intend to create primary/standby DB instances, they use the same parameter template. NOTICE: If you use a custom parameter template when creating a DB instance, the following specification-related parameters in the custom template are not delivered. Instead, the default values are used. maintenance_work_mem shared_buffers max_connections effective_cache_size You can modify the instance parameters as required after the DB instance is created. For details, see section Modifying Parameters in a Parameter Template.
Time Zone	You need to select a time zone for your instance based on the region hosting your instance. You can select a time zone during instance creation and change it later as needed.
Tag	Tags an RDS DB instance. This parameter is optional. Adding tags to RDS DB instances helps you better identify and manage the DB instances. A maximum of 20 tags can be added for each DB instance. If your organization has configured tag policies for RDS, add tags to DB instances based on the policies. If a tag does not comply with the policies, DB instance creation may fail. Contact your organization administrator to learn more about tag policies. After a DB instance is created, you can view its tag details on the Tags page. For details, see RDS for PostgreSQL Tags.

Required Duration and Quantity

**Table 5** Required duration and quantity
Parameter	Description
Required Duration	This option is available only for yearly/monthly DB instances. The system will automatically calculate the configuration fee based on the selected required duration. The longer the required duration is, the larger discount you will enjoy.
Auto-renew	This option is available only for yearly/monthly DB instances and is not selected by default. If you select this option, the auto-renew cycle is determined by the selected required duration.
Quantity	RDS supports batch creation of DB instances. If you intend to create primary/standby DB instances and set Quantity to 1, a primary DB instance and a synchronous standby DB instance will be created.

If you have any questions about the price, click Pricing details at the bottom of the page.

The performance of your DB instance depends on its configurations. Hardware configuration items include the instance specifications, storage type, and storage space.

Confirm the specifications for pay-per-use DB instances.
- If you need to modify your settings, click Previous.
- If you do not need to modify your settings, click Submit.
Skip 4 and 5 and go to 6.
Confirm the order for yearly/monthly DB instances.
- If you need to modify your settings, click Previous.
- If you do not need to modify your settings, click Pay Now.
Select a payment method and complete the payment.

This operation applies only to the yearly/monthly billing mode.
To view and manage your DB instance, go to the Instances page.
- When your DB instance is being created, the status is Creating. The status changes to Available after the instance is created.
- The automated backup policy is enabled by default. You can change it after the DB instance is created. An automated full backup is immediately triggered once your DB instance is created.
- After a DB instance is created, you can enter a description for it.
- The default database port is 5432. You can change it after a DB instance is created.
  
  You are advised to change the database port in a timely manner.
  
  For details, see Changing a Database Port.