Updated on 2026-01-05 GMT+08:00

Creating a Read Replica

Function

This API is used to create a read replica. Before calling this API:

Calling Method

For details, see Calling APIs.

Authorization Information

Each account has all the permissions required to call all APIs, but IAM users must be assigned the required permissions.

  • If you are using role/policy-based authorization, see Permissions and Supported Actions for details on the required permissions.
  • If you are using identity policy-based authorization, the following identity policy-based permissions are required.

    Action

    Access Level

    Resource Type (*: required)

    Condition Key

    Alias

    Dependency

    gaussdbformysql:instance:addReadOnlyNodes

    Write

    instance *

    • g:EnterpriseProjectId

    • g:ResourceTag/<tag-key>

    • gaussdb:instance:modify
    • gaussdb:instance:addNodes

    -

URI

POST /v3/{project_id}/instances/{instance_id}/nodes/enlarge

Table 1 URI parameters

Parameter

Mandatory

Type

Description

project_id

Yes

String

Definition

Project ID of a tenant in a region.

To obtain this value, see Obtaining a Project ID.

Constraints

N/A

Range

The value contains 32 characters. Only letters and digits are allowed.

Default Value

N/A

instance_id

Yes

String

Definition

Instance ID, which uniquely identifies an instance.

Constraints

N/A

Range

The value contains 36 characters with a suffix of in07. Only letters and digits are allowed.

Default Value

N/A

Request Parameters

Table 2 Request header parameters

Parameter

Mandatory

Type

Description

X-Auth-Token

Yes

String

Definition

User token. To obtain this value, call the IAM API for obtaining a user token.

The value of X-Subject-Token in the response header is the token value.

Constraints

N/A

Range

N/A

Default Value

N/A

X-Language

No

String

Definition

Request language type.

Constraints

N/A

Range

  • en-us

  • zh-cn

Default Value

en-us

Table 3 Request body parameters

Parameter

Mandatory

Type

Description

priorities

Yes

Array of integers

Definition

Failover priority of a read replica.

A smaller value indicates a higher priority. This priority determines the order in which read replicas are promoted when recovering from a primary node failure. Read replicas with the same priority have the same probability of being promoted to the new primary node. You can configure a failover priority for up to 9 read replicas, and the default priority for the remaining read replicas is -1, indicating these read replicas cannot be promoted to primary. You can change the failover priority of a read replica.

Constraints

N/A

Range

1–16

Default Value

N/A

is_auto_pay

No

String

Definition

Whether the order will be automatically paid.

Constraints

This parameter is only available for yearly/monthly instances. It does not affect the payment mode of automatic renewal.

Range

  • true: The order will be automatically paid.

  • false: The order will be manually paid.

Default Value

true

availability_zones

No

Array of strings

Definition

AZ. You can specify an AZ to create a read replica. If this parameter is not specified, an AZ is automatically assigned by default.

Constraints

The parameter is in the OBT phase. To use it, submit a service ticket.

To obtain the value, see the key availability_zone in az_status of Querying Database Specifications.

Note: Creating a read replica in a specified AZ may fail due to insufficient resources.

Range

To obtain the value, see the key availability_zone in az_status of Querying Database Specifications.

Default Value

N/A

Response Parameters

Status code: 201

Table 4 Response body parameters

Parameter

Type

Description

instance_id

String

Definition

Instance ID, which uniquely identifies an instance.

Range

N/A

node_names

Array of strings

Definition

Node names.

job_id

String

Definition

ID of the task for creating a read replica.

This parameter is only returned for pay-per-use read replicas.

Range

N/A

order_id

String

Definition

Order ID. This parameter is only returned for yearly/monthly read replicas.

Range

N/A

Status code: 400

Table 5 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Status code: 500

Table 6 Response body parameters

Parameter

Type

Description

error_code

String

Error code.

error_msg

String

Error message.

Example Request

Creating a read replica for a DB instance

POST https://{endpoint}/v3/054e292c9880d4992f02c0196d3ea468/instances/ba62a0b83a1b42bfab275829d86ac0fdin07/nodes/enlarge
{
  "priorities" : [ 1, 2 ]
}

Example Response

Status code: 201

Success.

{
  "instance_id" : "ba62a0b83a1b42bfab275829d86ac0fdin07",
  "node_names" : [ "gauss-ccf5_node03" ],
  "job_id" : "dff1d289-4d03-4942-8b9f-463ea07c000d"
}

SDK Sample Code

The SDK sample code is as follows.

Creating a read replica for a DB instance

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package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.gaussdb.v3.region.GaussDBRegion;
import com.huaweicloud.sdk.gaussdb.v3.*;
import com.huaweicloud.sdk.gaussdb.v3.model.*;

import java.util.List;
import java.util.ArrayList;

public class CreateGaussMySqlReadonlyNodeSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");
        String projectId = "{project_id}";

        ICredential auth = new BasicCredentials()
                .withProjectId(projectId)
                .withAk(ak)
                .withSk(sk);

        GaussDBClient client = GaussDBClient.newBuilder()
                .withCredential(auth)
                .withRegion(GaussDBRegion.valueOf("<YOUR REGION>"))
                .build();
        CreateGaussMySqlReadonlyNodeRequest request = new CreateGaussMySqlReadonlyNodeRequest();
        request.withInstanceId("{instance_id}");
        MysqlCreateReadonlyNodeRequest body = new MysqlCreateReadonlyNodeRequest();
        List<Integer> listbodyPriorities = new ArrayList<>();
        listbodyPriorities.add(1);
        listbodyPriorities.add(2);
        body.withPriorities(listbodyPriorities);
        request.withBody(body);
        try {
            CreateGaussMySqlReadonlyNodeResponse response = client.createGaussMySqlReadonlyNode(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

Creating a read replica for a DB instance

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# coding: utf-8

import os
from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkgaussdb.v3.region.gaussdb_region import GaussDBRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkgaussdb.v3 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.environ["CLOUD_SDK_AK"]
    sk = os.environ["CLOUD_SDK_SK"]
    projectId = "{project_id}"

    credentials = BasicCredentials(ak, sk, projectId)

    client = GaussDBClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(GaussDBRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = CreateGaussMySqlReadonlyNodeRequest()
        request.instance_id = "{instance_id}"
        listPrioritiesbody = [
            1,
            2
        ]
        request.body = MysqlCreateReadonlyNodeRequest(
            priorities=listPrioritiesbody
        )
        response = client.create_gauss_my_sql_readonly_node(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

Creating a read replica for a DB instance

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package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    gaussdb "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/gaussdb/v3"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/gaussdb/v3/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/gaussdb/v3/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")
    projectId := "{project_id}"

    auth := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        WithProjectId(projectId).
        Build()

    client := gaussdb.NewGaussDBClient(
        gaussdb.GaussDBClientBuilder().
            WithRegion(region.ValueOf("<YOUR REGION>")).
            WithCredential(auth).
            Build())

    request := &model.CreateGaussMySqlReadonlyNodeRequest{}
	request.InstanceId = "{instance_id}"
	var listPrioritiesbody = []int32{
        int32(1),
	    int32(2),
    }
	request.Body = &model.MysqlCreateReadonlyNodeRequest{
		Priorities: listPrioritiesbody,
	}
	response, err := client.CreateGaussMySqlReadonlyNode(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

For SDK sample code of more programming languages, see the Sample Code tab in API Explorer. SDK sample code can be automatically generated.

Status Code

For details, see Status Codes.

Error Code

For details, see Error Codes.