ALTER EXTERNAL DATA SOURCE (Transact-SQL)

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2016)yesAzure SQL DatabaseyesAzure SQL Data Warehouse yesParallel Data Warehouse

Modifies an external data source used to create an external table. The external data source can be Hadoop or Azure blob storage (WASB).

Syntax

-- Modify an external data source
-- Applies to: SQL Server (2016 or later)
ALTER EXTERNAL DATA SOURCE data_source_name SET
    {   
        LOCATION = 'server_name_or_IP' [,] |
        RESOURCE_MANAGER_LOCATION = <'IP address;Port'> [,] |
        CREDENTIAL = credential_name
    }  
    [;]  

-- Modify an external data source pointing to Azure Blob storage
-- Applies to: SQL Server (starting with 2017)
ALTER EXTERNAL DATA SOURCE data_source_name
    WITH (
        TYPE = BLOB_STORAGE,
        LOCATION = 'https://storage_account_name.blob.core.windows.net'
        [, CREDENTIAL = credential_name ]
    )  

Arguments

data_source_name Specifies the user-defined name for the data source. The name must be unique.

LOCATION = ‘server_name_or_IP’ Specifies the name of the server or an IP address.

RESOURCE_MANAGER_LOCATION = ‘<IP address;Port>’ Specifies the Hadoop Resource Manager location. When specified, the query optimizer might choose to pre-process data for a PolyBase query by using Hadoop’s computation capabilities. This is a cost-based decision. Called predicate pushdown, this can significantly reduce the volume of data transferred between Hadoop and SQL, and therefore improve query performance.

CREDENTIAL = Credential_Name Specifies the named credential. See CREATE DATABASE SCOPED CREDENTIAL (Transact-SQL).

TYPE = BLOB_STORAGE
Applies to: SQL Server 2017. For bulk operations only, LOCATION must be valid the URL to Azure Blob storage. Do not put /, file name, or shared access signature parameters at the end of the LOCATION URL. The credential used, must be created using SHARED ACCESS SIGNATURE as the identity. For more information on shared access signatures, see Using Shared Access Signatures (SAS).

Remarks

Only single source can be modified at a time. Concurrent requests to modify the same source cause one statement to wait. However, different sources can be modified at the same time. This statement can run concurrently with other statements.

Permissions

Requires ALTER ANY EXTERNAL DATA SOURCE permission.

Important

The ALTER ANY EXTERNAL DATA SOURCE permission grants any principal the ability to create and modify any external data source object, and therefore, it also grants the ability to access all database scoped credentials on the database. This permission must be considered as highly privileged, and therefore must be granted only to trusted principals in the system.

Examples

The following example alters the location and resource manager location of an existing data source.

ALTER EXTERNAL DATA SOURCE hadoop_eds SET
     LOCATION = 'hdfs://10.10.10.10:8020',
     RESOURCE_MANAGER_LOCATION = '10.10.10.10:8032'
    ;

The following example alters the credential to connect to an existing data source.

ALTER EXTERNAL DATA SOURCE hadoop_eds SET
   CREDENTIAL = new_hadoop_user
    ;