3 Replies Latest reply on Dec 6, 2017 11:16 AM by Toby Erkson

    What precisely is Tableau trying to do when it encounters "Incorrect data type"?

    christopher done

      I am currently writing a server for the TDS protocol (other examples of servers are: SQL Server), which provides a front-end for disparate ODBC clients within a large bank. Tableau is able to connect to it using the Microsoft SQL Server driver.

      Screenshot 2017-11-30 14.04.45.png

      I have bought Tableau Desktop Professional edition to test this.

      Screenshot 2017-11-30 14.10.37.png

      It seems to request a lot of meta information when connecting to the source, and I'm hitting a brick wall when I choose a database from the dropdown list, with the following error message:

      Screenshot 2017-11-30 13.55.18.png

       

      There is only this message, there are no details. I looked in the log files, and there is no mention of this message. I'm able to load up the data source with the list of databases. When I select my database from the dropdown list, that's when it makes at least the following queries:

       

      EXEC [flask].[sys].sp_fkeys 
      @pktable_name = NULL,
      @pktable_owner = NULL,
      @pktable_qualifier = NULL,
      @fktable_name = N'cucumbers',
      @fktable_owner = N'flask',
      @fktable_qualifier = N'flask';
      
      EXEC [flask].[sys].sp_statistics 
      @table_name = N'cucumbers',
      @table_owner = N'flask',
      @table_qualifier = N'flask',
      @is_unique = N'Y',
      @accuracy = N'Q';
      
      SELECT COLUMN_NAME, COLLATION_NAME, TABLE_NAME
      FROM INFORMATION_SCHEMA.COLUMNS
      WHERE TABLE_NAME = 'cucumbers'
      

       

      After the last one, it pops up with that error message.

       

      I'm basically at an impasse, because I don't know what Tableau wants from me. It's not open source, or I'd just grep the source and find what leads to this error. Could a developer from Tableau take a look at where this comes from? What's Tableau trying to do here? Is it because my reply for the third query is the wrong type of varchar/nvarchar? Is it that kind of type? Or is it from one of the other queries? If I double click on 'cucumbers' in the Table list, I see the same "Invalid data type." message (though it makes no query to the database at that point, so the invalidness seems to be cached).

       

      For each of the queries Tableau makes about metadata like this, I've gone and looked at what SQL Server returns and mimicked it. I suspect some field or return value somewhere is wrong, but without more info I'm doomed to find a needle in a haystack.

       

      I'd appreciate any kind of developer input on this!

       

      Cheers

        • 1. Re: What precisely is Tableau trying to do when it encounters "Incorrect data type"?
          Chris McClellan

          Can you post the table structure for cucumbers ?

           

          Just a screenshot from SSMS or similar that shows the column names and datatypes (no need to see the data, I think it's a datatype that's the problem here)

          • 2. Re: What precisely is Tableau trying to do when it encounters "Incorrect data type"?
            christopher done

            It's not a real table; the server pretends to have a table for the purpose of serving up a JSON feed.

             

            So far it hasn't transmitted any data for the table, because Tableau hasn't got as far as requesting it.

             

            Is it normal that no one from the Tableau team answers questions on this forum?

            • 3. Re: What precisely is Tableau trying to do when it encounters "Incorrect data type"?
              Toby Erkson

              christopher done wrote:

               

              ...

               

              Is it normal that no one from the Tableau team answers questions on this forum?

              Heh...yes, this can be frustrating until you understand how the forums here work.  There are only a handful of Tableau employees who are part of the forum team that try to answer questions since the forums are NOT part of Tableau Support   As such they can't possibly know everything about every Tableau product.  Employees from other departments within Tableau are encouraged to answer questions in the forums when they can but they do have their job that comes first.  These people typically answer questions in their knowledge domain, which is great!  It certainly would be nice to see more of these people, especially in the developer-side of the Tableau world.

               

              This means that the bulk of answers come from the Tableau community itself (you, me, Christopher, etc.) and that means it's all by volunteers.  So during, as well as outside, of our regular paying job we come here to help others when we can and as best as we can.  For example:  Since I know pretty much nothing about Java or Python I can't really help here, however, being a Tableau Server admin I am more active over in that forum.

               

              You'll find there is a lot more activity in the desktop/general forum since that is where the majority of Tableau users are found.  By their very nature server admins and programming developers are not as common and as such these forums have less activity within them BUT their activity tends to have more difficult questions as well.  Naturally there will be less volunteers in these sparser forums, too

               

              I hope this helps in understanding the forums.  Think of them as a quick approach to a question, like a Tier 0 support team, before actually contacting the Tier 1 team of the official Tableau Support group.