Can't query polybase external tables in MSSQL

[david_fetters]

Hey friends, we're running Alteryx 11.8 and MSSQL Enterprise 2016.  We've been experimenting with polybase tables stored in Azure blob storage but have a problem accessing them from Alteryx.

Whenever I query an external polybase table in MSSQL using Alteryx's Input tool and a standard Microsoft SQL connection, I receive the following error:

Error SQLExecute: [Microsoft][ODBC Driver 13 for SQL Server][Sql Server]The query processor could not produce a query plan because CURSOR fetch queries cannot reference external tables. Ensure that the input request does not contain remote UPDATE or DELETE on external tables.

The query I am using is of the form: SELECT * FROM table WHERE FilterField = 'OH'.

Any ideas on how I can get Alteryx to work with polybase tables?

[patrick_mcauliffe]

I’m new to polybase, but my understanding of this error message is in reference to the connection from the polybase to blob; not Alteryx to polybase.
Have you been able to use the same query successfully in any other tool?

[david_fetters · Accepted solution]

So I reran the query using an In-DB connection and it worked.  I then took the connection string created for the In-DB connection and used it in a normal input node (because the In-DB connection was only using SQL Native Client 11.1) and it worked as well.

The connection that is failing is using ODBC Driver 13, perhaps something related to the driver itself?  Not sure if anyone out there is using polybase or setup to try and duplicate this test but that's odd behavior.

[patrick_mcauliffe]

@david_fetters  It looks like you've solved this on your own then.  Polybase must require some of the features in the SQL Server Native Client connection:
https://docs.microsoft.com/en-us/sql/relational-databases/native-client/when-to-use-sql-server-nativ...

[david_fetters]

I'll begrudgingly give myself the solution on this one, as the work around might help someone else in the future.  I would like to figure out why the external tables fail with the v 13 driver, but I think that's beyond my ability at this point.