3 Replies Latest reply on Jan 13, 2019 12:22 PM by Bruce Segal

    Tableau Prep Input Node Collation Mismatch Error

    Baker Lee

      I cannot get my Prep flow to run as it is giving me the system error below.


      My flow has 3 inputs: two CSVs (~10MB and ~150 MB) and one .hyper output from another flow (~200 kb). The flow usually takes a minute to load, and after the first time, the flow usually executes correctly. This error only started today after I saved over the input files with new data of the same name and file path.


      Here is the exact text of the error:

      System Error: Unable to run input node: Failure evaluating to database: ERROR: collation mismatch, use COLLATE statements to resolve


      Please help me as there is nothing I have found to solve this issue and it is crucial to my daily workflow. Let me know if I can provide any more information.


      Thanks to anyone who can help!


        • 1. Re: Tableau Prep Input Node Collation Mismatch Error
          Jonathan Drummey

          Hi, I'd suggest reaching out to Tableau support on this one.

          • 3. Re: Tableau Prep Input Node Collation Mismatch Error
            Bruce Segal

            Hi Baker Lee I got a similar message using the version of Superstore data that comes with Tableau Prep; 'System error: Unable to run input node. Failure evaluating to database, all inputs to union must have matching column types."


            See screen shot below.


            This happened to me twice now in the same situation and I'm frustrated. I've had to rebuild my flow from scratch twice now, which gives me no confidence in Tableau Prep for when I use it with real data.


            It happened in the same situation. I had the flow up and working well. And then I made a change to one of the data inputs that feed into a Union. In this case I "un-removed" one column that I had "removed" in the input step, and removed a different one. They're effectively the same columns, and both were measures, in decimal data format. The only visible difference is that they had different column names.


            The result is that no data displays when I click on the Union 1. That result is consistent with the error message, but there's no information in the error message to help me diagnose if I did something wrong, or which fields are not "matching column types."