Error while trying to query external tables in Serverless SQL pools - azure

Question

I am trying to run SELECT * from [dbo].[<table-name>]; queries using JDBC driver on an external table I created in my serverless SQL pool in Azure Synapse using ADLS Gen2 as the storage but getting this error :-
External table 'dbo' is not accessible because location does not exist or it is used by another process.
I get the same error with SELECT * from [<table-name>]; as well. I've tried giving all the required permissions in the storage account as mentioned here https://learn.microsoft.com/en-us/azure/synapse-analytics/sql/resources-self-help-sql-on-demand#query-execution but still getting the same.
Can someone please help me out with this?

Answer 1

This type of error (if you're sure both file exist and it's not used by another process) usually could mean:
As the documentation you linked says, Serverless SQL pool can't access the file because your Azure Active Directory identity doesn't have rights to access the file or because a firewall is blocking access to the file. By default, serverless SQL pool is trying to access the file using your Azure Active Directory identity. To resolve this issue, you need to have proper rights to access the file. Easiest way is to grant yourself 'Storage Blob Data Contributor' role on the storage account you're trying to query.
You have done something wrong when you created the external table. For example, if you have defined your external table in a folder that doesn't actually exist in your storage, you will receive the same error provided, so check out for that (see the SQL script example below for a correct creation of the external table)
-- Create external data source for the storage
CREATE EXTERNAL DATA SOURCE [Test] WITH
(
LOCATION = 'https://<StorageAccount>.blob.core.windows.net/<Container>'
)
-- Create external file format for csv
CREATE EXTERNAL FILE FORMAT [csv] WITH
(
FORMAT_TYPE = DELIMITEDTEXT,
FORMAT_OPTIONS (
FIELD_TERMINATOR = ',')
)
-- Create external table
CREATE EXTERNAL TABLE [dbo].[TableTest]
(
[Col1] VARCHAR(2),
[Col2] INT,
[Col3] INT
)
WITH
(
LOCATION = '<FolderIfExist>/<FileName>.csv',
DATA_SOURCE = [DSTest],
FILE_FORMAT = [csv]
)