In my most recent blog post, Unified data platform and data virtualization through PolyBase: Part Two, I provided a demo of data virtualization through PolyBase.
While setting up the SQL PolyBase demo to fetch data from external sources, I faced a couple of issues. Although I fixed the issues quickly, I thought it would be good to consolidate and present them in one place so anyone having the same problems can benefit. So, let’s get started.
ERROR: You can install PolyBase on only one SQL Server instance per machine.
Figure 1 - First issue, error
This error is self-explanatory. Instances can’t share PolyBase, and more than one instance on a machine can’t have it simultaneously. In my case, I already installed SQL Polybase on another instance, so the error occurred.
I had to remove Polybase from the instance where I previously installed it. After that, I re-ran the SQL setup and selected to install the PolyBase feature for the new instance, and it went fine.
Figure 2 - First issue, resolved
ERROR : Support for external data source of type HADOOP is not enabled. To enable, set ‘hadoop connectivity’ to desired value.
The error occurred when I created the external data source of TYPE = HADOOP.
Figure 3 - Second issue, error
The system throws this error in two cases:
You can use the following query to set the parameter value:
EXEC sp_configure @configname = 'hadoop connectivity', @configvalue = 7; Go Reconfigure
I checked for the parameter value on my instance, and I set it up correctly, as shown in the following image:
Though the need to restart SQL services wasn’t documented, a restart fixed the issue for me. I re-ran the Create External Data Source query in Step 3 of the PolyBase demo post, and it went fine.
Figure 5 - Second issue, resolved
ERROR: Incorrect syntax near EXTERNAL
The error occurred when I ran the following query to create the external file format:
CREATE EXTERNAL FILE FORMAT TextFileFormat WITH ( FORMAT_TYPE = DELIMITEDTEXT, FORMAT_OPTIONS (FIELD_TERMINATOR =',',USE_TYPE_DEFAULT = TRUE))
This error is misleading because it looks like a syntactical error. However, it occurs when you don’t enable the PolyBase feature properly.
I ran the following query to fix the issue:
EXEC sp_configure 'polybase enabled', 1; Go Reconfigure
It’s critical that you run the
Reconfigure query. When you use sp_configure to change
a system configuration, you must run a
Reconfigure to finalize the change.
That does it for the errors I encountered in the PolyBase demo and their resolutions. Thanks for reading!
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