ALTER EXTERNAL VOLUME

Modifies the properties for an existing external volume.

See also:

CREATE EXTERNAL VOLUME , DROP EXTERNAL VOLUME , SHOW EXTERNAL VOLUMES , DESCRIBE EXTERNAL VOLUME

Syntax

ALTER EXTERNAL VOLUME [ IF EXISTS ] <name> ADD STORAGE_LOCATION =
                                             (
                                             NAME = '<storage_location_name>'
                                             cloudProviderParams
                                             )

ALTER EXTERNAL VOLUME [ IF EXISTS ] <name> REMOVE STORAGE_LOCATION '<storage_location_name>'

ALTER EXTERNAL VOLUME [ IF EXISTS ] <name> SET ALLOW_WRITES = { TRUE | FALSE }

ALTER EXTERNAL VOLUME [ IF EXISTS ] <name> SET COMMENT = '<string_literal>'
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Where:

cloudProviderParams (for Amazon S3) ::=
  STORAGE_PROVIDER = 'S3'
  STORAGE_AWS_ROLE_ARN = '<iam_role>'
  STORAGE_BASE_URL = 's3://<bucket>[/<path>/]'
  [ ENCRYPTION = ( [ TYPE = 'AWS_SSE_S3' ] |
              [ TYPE = 'AWS_SSE_KMS' [ KMS_KEY_ID = '<string>' ] ] |
              [ TYPE = 'NONE' ] ) ]
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cloudProviderParams (for Google Cloud Storage) ::=
  STORAGE_PROVIDER = 'GCS'
  STORAGE_BASE_URL = 'gcs://<bucket>[/<path>/]'
  [ ENCRYPTION = ( [ TYPE = 'GCS_SSE_KMS' ] [ KMS_KEY_ID = '<string>' ] |
              [ TYPE = 'NONE' ] ) ]
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cloudProviderParams (for Microsoft Azure) ::=
  STORAGE_PROVIDER = 'AZURE'
  AZURE_TENANT_ID = '<tenant_id>'
  STORAGE_BASE_URL = 'azure://<account>.blob.core.windows.net/<container>[/<path>/]'
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Parameters

name

Specifies the identifier for the external volume to alter.

If the identifier contains spaces or special characters, the entire string must be enclosed in double quotes. Identifiers enclosed in double quotes are also case-sensitive.

For more information, see Identifier requirements.

ADD STORAGE_LOCATION

Adds a named storage location to the external volume definition. To add multiple storage locations, execute an ALTER EXTERNAL VOLUME statement for each storage location.

Note

Iceberg tables write to and read from the first storage location in the set that is located in the same region as your Snowflake account. To view the external volume definition and storage location regions, execute DESCRIBE EXTERNAL VOLUME.

REMOVE STORAGE_LOCATION

Removes the specified storage location from the external volume definition. To remove multiple storage locations, execute an ALTER EXTERNAL VOLUME statement for each storage location.

Note

The ALTER EXTERNAL VOLUME statement fails if you attempt to remove the active storage location used by Iceberg tables in your account.

SET ...

Specifies one or more properties/parameters to set for the external volume (separated by blank spaces, commas, or new lines):

ALLOW_WRITES = { TRUE | FALSE }

Specifies whether write operations are allowed for the external volume.

  • TRUE specifies that write operations are allowed. This parameter must be set to TRUE for Snowflake-managed Iceberg tables.

  • FALSE specifies that write operations aren’t allowed. You can’t change the value of this parameter to FALSE if there are Snowflake-managed Iceberg tables associated with the external volume.

COMMENT = 'string_literal'

String (literal) that specifies a comment for the external volume.

Cloud provider parameters (cloudProviderParams)

Amazon S3

STORAGE_PROVIDER = 'S3'

Specifies the cloud storage provider that stores your data files.

STORAGE_AWS_ROLE_ARN = iam_role

Specifies the Amazon Resource Name (ARN) of the AWS identity and access management (IAM) role that grants privileges on the S3 bucket containing your data files. For more information, see Configuring secure access to Amazon S3.

STORAGE_BASE_URL = 's3://bucket[/path/]'

Specifies the base URL for your cloud storage location, where:

  • bucket is the name of an S3 bucket that stores your data files.

  • path is an optional path that can be used to provide granular control over objects in the bucket.

ENCRYPTION = ( [ TYPE = 'AWS_SSE_S3' ] | [ TYPE = 'AWS_SSE_KMS' [ KMS_KEY_ID = 'string' ] ] | [ TYPE = 'NONE' ] )

Specifies the properties needed to encrypt data on the external volume.

TYPE = ...

Specifies the encryption type used. Possible values are:

KMS_KEY_ID = 'string' (applies to AWS_SSE_KMS encryption only)

Optionally specifies the ID for the AWS KMS-managed key used to encrypt files written to the bucket. If no value is provided, your default KMS key is used to encrypt files for writing data.

Note that this value is ignored when reading data.

Google Cloud Storage

STORAGE_PROVIDER = 'GCS'

Specifies the cloud storage provider that stores your data files.

STORAGE_BASE_URL = 'gcs://bucket[/path/]'

Specifies the base URL for your cloud storage location, where:

  • bucket is the name of a Cloud Storage bucket that stores your data files.

  • path is an optional path that can be used to provide granular control over objects in the bucket.

ENCRYPTION = ( [ TYPE = 'GCS_SSE_KMS' ] [ KMS_KEY_ID = 'string' ] | [ TYPE = 'NONE' ] )

Specifies the properties needed to encrypt data on the external volume.

TYPE = ...

Specifies the encryption type used. Possible values are:

KMS_KEY_ID = 'string' (applies to GCS_SSE_KMS encryption only)

Specifies the ID for the Cloud KMS-managed key that is used to encrypt files written to the bucket.

This value is ignored when reading data. The read operation should succeed if the service account has sufficient permissions to the data and any specified KMS keys.

Microsoft Azure

STORAGE_PROVIDER = 'AZURE'

Specifies the cloud storage provider that stores your data files.

AZURE_TENANT_ID = 'tenant_id'

Specifies the ID for your Office 365 tenant that the allowed and blocked storage accounts belong to. An external volume can authenticate to only one tenant, so the allowed and blocked storage locations must refer to storage accounts that all belong to this tenant.

To find your tenant ID, log into the Azure portal and click Azure Active Directory » Properties. The tenant ID is displayed in the Tenant ID field.

STORAGE_BASE_URL = 'azure://account.blob.core.windows.net/container[/path/]'

Specifies the base URL for your cloud storage location, where:

  • account is the name of your Azure account; for example, myaccount.

  • container is the name of an Azure container that stores your data files.

  • path is an optional path that can be used to provide granular control over logical directories in the container.

Access control requirements

A role used to execute this SQL command must have the following privileges at a minimum:

Privilege

Object

Notes

OWNERSHIP

External volume

OWNERSHIP is a special privilege on an object that is automatically granted to the role that created the object, but can also be transferred using the GRANT OWNERSHIP command to a different role by the owning role (or any role with the MANAGE GRANTS privilege).

For instructions on creating a custom role with a specified set of privileges, see Creating custom roles.

For general information about roles and privilege grants for performing SQL actions on securable objects, see Overview of Access Control.

Usage notes

Regarding metadata:

Attention

Customers should ensure that no personal data (other than for a User object), sensitive data, export-controlled data, or other regulated data is entered as metadata when using the Snowflake service. For more information, see Metadata Fields in Snowflake.

Examples

The following example removes the storage location named my-us-east-1 from the exvol1 external volume:

ALTER EXTERNAL VOLUME exvol1 REMOVE STORAGE_LOCATION 'my-us-east-1';
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The following examples add a storage location to an external volume:

Amazon S3

ALTER EXTERNAL VOLUME exvol1
  ADD STORAGE_LOCATION =
    (
      NAME = 'my-s3-us-central-2'
      STORAGE_PROVIDER = 'S3'
      STORAGE_BASE_URL = 's3://my_bucket_us_central-1/'
      STORAGE_AWS_ROLE_ARN = 'arn:aws:iam::123456789012:role/myrole'
    );
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Google Cloud Storage

ALTER EXTERNAL VOLUME exvol2
  ADD STORAGE_LOCATION =
    (
      NAME = 'my-gcs-europe-west4'
      STORAGE_PROVIDER = 'GCS'
      STORAGE_BASE_URL = 'gcs://my_bucket_europe-west4/'
    );
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Microsoft Azure

ALTER EXTERNAL VOLUME exvol3
  ADD STORAGE_LOCATION =
    (
      NAME = 'my-azure-japaneast'
      STORAGE_PROVIDER = 'AZURE'
      STORAGE_BASE_URL = 'azure://sfcdev1.blob.core.windows.net/my_container_japaneast/'
      AZURE_TENANT_ID = 'a9876545-4321-987b-b23c-2kz436789d0'
    );
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