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E-MapReduce:ModifyCu

Last Updated:Dec 24, 2025

You can use this API to change the number of Compute Units (CUs) in a compute group of a Serverless StarRocks instance.

Operation description

Before you call this API, make sure that you understand the billing methods and billable items of Serverless StarRocks.

When you call this API, note the following:

  • This operation is supported only for Standard Edition instances. It is not supported for Starter Edition instances.

  • You can increase the number of disks only for instances with a standard compute group specification.

  • The instance must be in the Running state.

After you change the number of CUs, the billing for the instance is updated as follows:

  • Pay-as-you-go: You are billed based on the new number of CUs.

  • Subscription: A supplementary fee is charged. This fee is calculated based on the price difference between the old and new configurations and the remaining subscription period. The remaining period starts at 00:00 on the following day and ends when the subscription expires.

Try it now

Try this API in OpenAPI Explorer, no manual signing needed. Successful calls auto-generate SDK code matching your parameters. Download it with built-in credential security for local usage.

Test

RAM authorization

The table below describes the authorization required to call this API. You can define it in a Resource Access Management (RAM) policy. The table's columns are detailed below:

  • Action: The actions can be used in the Action element of RAM permission policy statements to grant permissions to perform the operation.

  • API: The API that you can call to perform the action.

  • Access level: The predefined level of access granted for each API. Valid values: create, list, get, update, and delete.

  • Resource type: The type of the resource that supports authorization to perform the action. It indicates if the action supports resource-level permission. The specified resource must be compatible with the action. Otherwise, the policy will be ineffective.

    • For APIs with resource-level permissions, required resource types are marked with an asterisk (*). Specify the corresponding Alibaba Cloud Resource Name (ARN) in the Resource element of the policy.

    • For APIs without resource-level permissions, it is shown as All Resources. Use an asterisk (*) in the Resource element of the policy.

  • Condition key: The condition keys defined by the service. The key allows for granular control, applying to either actions alone or actions associated with specific resources. In addition to service-specific condition keys, Alibaba Cloud provides a set of common condition keys applicable across all RAM-supported services.

  • Dependent action: The dependent actions required to run the action. To complete the action, the RAM user or the RAM role must have the permissions to perform all dependent actions.

Action

Access level

Resource type

Condition key

Dependent action

sr:ModifyCu

get

*Instance

acs:sr:{#regionId}:{#accountId}:instance/{#InstanceId}

None None

Request syntax

POST /webapi/resourceChange/modifyCu HTTP/1.1

Request parameters

Parameter

Type

Required

Description

Example

InstanceId

string

Yes

The instance ID.

c-b25e21e24388****

NodeGroupId

string

Yes

The compute group ID.

ng-3d5ce6454354****

Target

integer

Yes

The target number of CUs.

4

FastMode

boolean

No

Specifies whether to restart the instance in fast restart mode. The default value is false.

  • true: Restarts the compute nodes in fast restart mode. The compute nodes are restarted in batches. Nodes within a batch are restarted in parallel, and batches are processed sequentially.

  • false: Restarts the compute nodes in rolling restart mode.

true

PromotionOptionNo

string

No

Response elements

Element

Type

Description

Example

object

HttpStatusCode

integer

The HTTP status code.

200

RequestId

string

The request ID.

32A44F0D-BFF6-5664-999A-218BBDE7****

Success

boolean

Indicates whether the request was successful.

false

ErrCode

string

The error code.

InvalidParams

ErrMessage

string

The error message.

Invalid params: [instance not exists].

Data

integer

The order ID.

24151320976****

AccessDeniedDetail

string

Details about the access denial.

{ "PolicyType": "AccountLevelIdentityBasedPolicy", "AuthPrincipalOwnerId": "xxx", "EncodedDiagnosticMessage": "xxx", "AuthPrincipalType": "xxx", "AuthPrincipalDisplayName": "xxx", "NoPermissionType": "ImplicitDeny", "AuthAction": "sr:xxx" }

Examples

Success response

JSON format

{
  "HttpStatusCode": 200,
  "RequestId": "32A44F0D-BFF6-5664-999A-218BBDE7****",
  "Success": false,
  "ErrCode": "InvalidParams",
  "ErrMessage": "Invalid params: [instance not exists].\n",
  "Data": 0,
  "AccessDeniedDetail": "{     \"PolicyType\": \"AccountLevelIdentityBasedPolicy\",     \"AuthPrincipalOwnerId\": \"xxx\",     \"EncodedDiagnosticMessage\": \"xxx\",     \"AuthPrincipalType\": \"xxx\",     \"AuthPrincipalDisplayName\": \"xxx\",     \"NoPermissionType\": \"ImplicitDeny\",     \"AuthAction\": \"sr:xxx\"   }"
}

Error codes

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.