3 Replies Latest reply on Jul 6, 2018 3:26 PM by Deepak Rai

    Joining multiple tables becomes extremely slow

    Siebe Bosch

      Dear community,

       

      I have a geographic file (shapefile) that constists of around 40 polygons
      I have an Excel-document that has several tabpages, each containing a few hundred records.

       

      The process of joining tables however is extremely slow and it looks like the time required grows exponentially with the number of joins I create.

       

      In 8 Excel tabpages I have data that refers to the polygons in the shapefile.
      So I try to create 8 joins between the geographic data source and the excel tab page. Like so:

       

      connections.jpg

       

      The problem is: after the third join the whole process becomes so slow that Tableau becomes non-responsive for a long time.
      Only after the process has finished am I allowed to change the join type from an inner join to a left join (which appears to be a LOT faster).

       

      An example of the data:

       

      Geographic file contains polygons, each of which has an ID in the field owmident. Here's one of them, displayed on top of Openstreetmap.

      connections_004.jpg

       

      The Excel file, e.g. the tab ESF1.Score contains water quality values for each of the polygons:

      connections_002.jpg

       

      Question: is there a smarter way to import this data? For starters, I do not need any interaction between data on the various Excel-sheets. So is it really necessary for Tableau to create some sort of huge internal table that contains mililons of unique combinations of my records?

       

      In stead of this:

      connections_003.jpg

      I would much rather have had something like this:

      connections.png

      Is this even possible in Tableau? Or are there better ways to prepare my data for Tableau?

       

      Thanks for your ideas.