2 Replies Latest reply on Feb 27, 2017 1:43 AM by Matthias Maes

    How to recognize deterministic calculations in Tableau?

    Matthias Maes

      I would like to optimize the performance of my workbook at Tableau server by putting as many of my calculated fields as possible in the extract. So the calculated fields are computed in advance and stored in the extract.

       

      I have read that extracts can be optimized, but only deterministic calculations. So the following types of calculated fields ARE NOT materialized:

      - Calculations that use unstable functions such as NOW() and TODAY()

      - Calculations that use external functions such as RAWSQL and R

      - Table calculations

       

      The results of non-deterministic calculations, such as those that involve a parameter or aggregations (such as sum or average) that are calculated at runtime, cannot be stored.

       

      • How can I recognize if a calculation is already stored in the extract?
      • What about LOD calculated fields (like FIXED, INCLUDE, ...)?

       

      Thanks,

      MM

        • 1. Re: How to recognize deterministic calculations in Tableau?
          Tharashasank Davuluru

          Hi Matthisas,

          How can I recognize if a calculation is already stored in the extract?

          As per my understanding :

          A Tableau Server published data source has the metadata about calc fields,hierarchies, colors, bins, sets, groups, etc. and the connection

          information for the underlying data.Except for temp tables, Tableau does not write back to the data source.That's been a feature request for awhile now to support various data entry & comment use cases.

           

          The calculated fields are saved in the workbooks AND are specifically associated with a given data source.

          If you replace data source by another (where data structure remains the same none the less), the calculated fields are gone.

           

          There are easier options for replacing data sources that require less labor, see Recommended practices for sharing/re-using Tableau Data Extracts (.tde's) for examples. There's also opening up the workbook XML.

           

          Thanks,

          Tharashasank

          • 2. Re: How to recognize deterministic calculations in Tableau?
            Matthias Maes

            After making an extract, you can right click on the extract and select View data...

            In there each column represents a dimension which was stored in the extract.

            You'll see that certain dimension from your workbook are not in there. So then you know that these are non-deterministic calculations which can not be stored.

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