external-tables - Azure Synapse 分析：访问外部表时出错

Question

无法执行查询。错误：文件“ https://track2gen2storage.blob.core.windows.net/\sourcedata\sample.csv ”无法打开，因为它不存在或被另一个进程使用。

我们执行了这些步骤：-

create database SalesdataDemo
use salesdataDemo
-----create master key
CREATE MASTER KEY ENCRYPTION BY PASSWORD = <Password>;
SELECT *
FROM sys.symmetric_keys AS SK
WHERE SK.name = '##MS_DatabaseMasterKey##';

CREATE DATABASE SCOPED CREDENTIAL ADL_User
WITH
IDENTITY = '<client_id>@<OAuth_2.0_Token_EndPoint>',Secret = <Key>

CREATE DATABASE SCOPED CREDENTIAL adls_credential
WITH IDENTITY ='SHARED ACCESS SIGNATURE',
SECRET = <azure_storage_account_key>

CREATE EXTERNAL DATA SOURCE adlsdatasource
WITH
( LOCATION = 'https://track2gen2storage.blob.core.windows.net',
CREDENTIAL = adls_credential
) ;

CREATE EXTERNAL FILE FORMAT adls_csv
WITH (
FORMAT_TYPE = DELIMITEDTEXT,
FORMAT_OPTIONS ( FIELD_TERMINATOR = ',', STRING_DELIMITER = '"', FIRST_ROW = 2 )
);


CREATE EXTERNAL TABLE sampledata ( <ColumnName><Datatype>)
WITH (
LOCATION = '/sourcedata/sample.csv',
DATA_SOURCE = adlsdatasource,
FILE_FORMAT = adls_csv
)

select * from sampledata

Answer 1

我认为问题在于您的外部表位置以 / 开头。尝试将其更改为：

CREATE EXTERNAL TABLE sampledata ( <ColumnName><Datatype>)
WITH (
LOCATION = 'sourcedata/sample.csv',
DATA_SOURCE = adlsdatasource,
FILE_FORMAT = adls_csv
)

这是您也可以查看参考的文档： https ://docs.microsoft.com/en-us/azure/synapse-analytics/sql/create-use-external-tables

还有一个问题，为什么需要名为 ADL_User 的数据库范围凭证？