Azure SQL Data Warehouse and PolyBase can't read CSV files generated using U-SQL and ADLA

Question

I have a U-SQL script that generates a CSV file in Azure storage and an external table in Azure SQL Data Warehouse (SDW) using PolyBase to read that CSV file.

When the CSV file is generated using the U-SQL script, SDW is unable to read the data and throws the exception:

Msg 110802, Level 16, State 1, Line 152 110802;An internal DMS error occurred that caused this operation to fail. Details: Exception: Microsoft.SqlServer.DataWarehouse.DataMovement.Common.ExternalAccess.HdfsAccessException, Message: Java exception raised on call to HdfsBridge_RecordReaderFillBuffer: Error [Unable to retrieve Java exception.] occurred while accessing external file [/csv/2015-02-13/all.csv][0].

However if I download that CSV file to a local drive and upload it exactly as is with no modifications to the exact same location with the exact same file name, SDW can run queries against it with no problems.

Any ideas?

Answer 1

This is unexpected and the SQL Data Warehouse team would like to investigate this issue. Can you create a support ticket by following the instructions in the link below?

https://azure.microsoft.com/en-us/documentation/articles/sql-data-warehouse-get-started-create-support-ticket/

If you don't have a support plan (required to create a technical support case), please email the SQL Data Warehouse team directly at [email protected] and include your server name, database name, error message and the approximate timestamp of this error.