3 Replies Latest reply on Jun 15, 2018 11:30 AM by Jeevan Krishna

    Blending with three different data sources - Need help!

    Data Modeler

      I have three data sources, say A, B and C - the common field in the three data sources is Date and the field of my interest is Sold Quantity. I am trying to blend the data across the three sources by using date like mmm/yyyy and get the  overall monthly quantity across the three data sets from three different sources. Let's say A is my primary data source. I am able to successfully blend A with B using date in mmm/yyyy format. I am also able to blend A with C using the same date format on a separate worksheet and get the right quantity. However, when I do the two blends (A with B and A with C) on a single worksheet - one of the blends starts showing incorrect results and the monthly quantity gets incorrect - is this expected behaviour. Can I not blend more than two secondary sources with a primary on a single worksheet.

       

      I would greatly appreciate any help - I have spend hours figuring this out but no success! Thank you.

        • 1. Re: Blending with three different data sources - Need help!
          Jeevan Krishna

          Hi Data Modeler ,

           

          I have an idea which I cannot test right away.

          1. In your 2nd and 3rd data sources. duplicate the date field.
          2. Go to Data menu on top and go to Edit Relationships (Data -> Edit Relationships)
          3. Create a custom relationship between the 2 new created in 2nd and 3rd source.
          4. Now try to recreate the sheet and link the 2nd and 3rd data source.

           

          May this work and Hope this helps.

          • 2. Re: Blending with three different data sources - Need help!
            Data Modeler

            Hi Jeevan - Thank you so much. I was able to correctly blend using your method! I am curious - What happened at the tableau backend - Why did the blend worked correctly on the worksheet after I duplicated the date fields in secondary data sources? Any ideas and explanation?

             

            Another quick question - How do I show grand totals on the blended data? Thank you!

            • 3. Re: Blending with three different data sources - Need help!
              Jeevan Krishna

              Hi ,

               

              • I guess there are minor differences in data granularity between the 3 different sources.
              • 1 limitation I understood when you mentioned you need to blend 3 different sources and use all of them in 1 single view, the issue will be linking 1 datasource to 2 other datasources using the same date field, which cannot happen when you have the normal single date field.
              • So, the solution I thought of included duplicating the fields and linking them, which will let you combine the fields on the same level of granularity.