2 Replies Latest reply on Dec 22, 2017 12:22 PM by Daniel Stanish

    Preferred Table Join Order in Tableau Data Source

    Daniel Stanish

      Good day all. I've searched through the forums, and I didn't see an answer, so I thought I'd pose it here. When creating a data source joining multiple tables together, is there a "best" order for performance. IE as larger tables first, smaller tables? Indexed, not indexed? If combining different data source types, is one type (e.g. Oracle) better to have at the root? Does it even matter?

       

      Thanks!

       

      -Dan

        • 1. Re: Preferred Table Join Order in Tableau Data Source
          Nicole Le Prohn

          Hi Dan,

          I just do SQL so not sure if this is helpful. For me it always depends on what is in the tables and now they link. I tend to put the table that has the most data I want first, and then join the others as needed. Note that it is the amount of data I'm pulling, not the size of the original table, that I look at.

           

          If, however, tables are at different levels - rows in one are states and in another are counties - then I have the table at the lowest level first, regardless of size. I'm 100% self taught at SQL and so I muddle my way thru but this is what has worked for me.

           

          Hope this helps. I'll be interested in what others say.

          Nicole

          1 of 1 people found this helpful
          • 2. Re: Preferred Table Join Order in Tableau Data Source
            Daniel Stanish

            Hi Nicole,

            What you've said makes sense, and was my understanding as a best practice for SQL join performance! I am curious if this model is how one is to build the relationships in Tableau. I'll try some tests to see if I can find a difference.