2 Replies Latest reply on May 21, 2018 9:27 PM by Olivia Shen

    Not showing sample values nor results for wildcard union

    Olivia Shen

      Hi all,


      Glad to find this place. I'm new to Tableau Prep and trying to reproduce a data set that I used to build in Power Query.


      Something strange happens when I use wildcard union as a data input. If I select Single table, sample value is shown and all following steps (join with another table, etc.) show result sets as well. However, when I select Wildcard Union, sample value is no longer there and all following result sets are just empty. (see pics below)


      I have several Wildcard Union data inputs, and wield enough, one of them does work but all the other just do not perform properly. They're all csv files sitting in separate folders. I also edit the connection to select another file in the folder as a start point, still the same issue. To use all data rather than default sample amount does not make a difference. Creating a new flow to start over again does not fix the problem either.



      Single Table works fine


      After switching to Wildcard Union, Sample Values no longer appear


      All following result sets show nothing


      Could anyone suggest what's the possible issues here and how to fix it?


      Appreciate in advance,



        • 1. Re: Not showing sample values nor results for wildcard union
          Nathan Panuco

          I've had this happen when my columns didn't quite match up nicely within my CSVs. I went through each file and "copy/pasted" the header row from the first CSV and that fixed my issue. That may not be your exact problem, but potentially there's an issue with the data coming into Prep.


          Try adding one file at a time to the wildcard union and see which one causes the data to disappear.


          Also, Prep might still be churning away - have you opened Task Manager to see if CPU, Memory or Ethernet is maxed out?

          1 of 1 people found this helpful
          • 2. Re: Not showing sample values nor results for wildcard union
            Olivia Shen

            Hi Nathan,


            Thanks for the reply.


            I've imported different files to test it and finally revealed that this issue was caused by brackets "[", "]" in my files names. Have no idea why it's not working, might have something to do with SharePoint as well. Anyway, after getting rid of the brackets, wildcard union works fine for all the data sources.

            1 of 1 people found this helpful