7 Replies Latest reply on Jun 6, 2018 7:04 AM by Toby Erkson Branched to a new discussion.

    When To Use Which Connection (Live vs Extract)

    Benjamin Cole



      I have a handful of different data sources,

      - Google analytics

      - 20k row excel sheets

      - Google Sheets

      - Facebook, Lindex

      - MySQL database



      Lets Assume that each data source has to be updated once a month, even though in reality they each are different.

      What do I need to consider when thinking about the connection type?  Speed? Update needs? etc?


      Also...I have a handful of different platforms from which I extract data.

      How ought I store each extract most simply so as to create auto updates, or at least simple manual updates?

      Is a Tableau Server and published Tableau data sources in my future?



        • 1. Re: When To Use Which Connection (Live vs Extract)
          Boas Lee

          Hi Benjamin,


          Tableau Desktop allows two different types of connections (live and extract).


          In general, it is always better to use an extract. Tableau Data Extract (TDE) are Tableau Software's file type and is created to work optimally with Tableau products. Using an extract will not only saves resources from the database (does not query the data base) but will allow the user to get information offline. That being said, depending on how frequent the data is being updated, some choose to use a live connection. If the data source updates frequently, Tableau Desktop will not show the updated data. Since Tableau Desktop will query the extract, it is expected that the data being seen might be old. If it is important to have the most updated data (live information), using an extract may not be the best. It is important to keep in mind that it is also possible to schedule a refresh for a extract on Tableau Server. If you know the data is being updated ever month at a particular time, it should be possible to schedule a refresh every month getting the most recent date.


          I found a link to a whitepaper that addresses the concepts discussed above and should help in working both with the extracts and live connections:




          Hope this helps.




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          • 2. Re: When To Use Which Connection (Live vs Extract)
            Benjamin Cole

            Hi Boas,


            Thanks for the response and white paper. 


            Sounds like I'd typically only use a live connection when I need up to date numbers, primarily when connecting to a database.  If connecting to a local static excel doc on my machine would a live connection serve any purpose?  Will an extract be faster?


            Thanks again,

            • 3. Re: When To Use Which Connection (Live vs Extract)
              Boas Lee

              Hi Benjamin,


              That is correct. An extract should be faster compared to using a live connection. This being said, please keep in mind that all of this is workbook specific. In general, it is better to use an  extract over a live connection. It also may be possible that a live connection could be faster than an extract.




              • 4. Re: When To Use Which Connection (Live vs Extract)
                Toby Erkson

                You don't want everything to be an extract as that will impact the Tableau Server's performance and that can cause others to get rather grumpy


                I encourage my users to use a live connection unless speed is of the essence and/or query/rendering times are taking too long -- a relative term but up to 15 - 30 seconds seems to be the threshold of acceptance and beyond that, "extract time!".


                The data source doesn't matter, it's how much is being pulled.


                For Excel a live connection is typically best.  If you're pulling thousands of rows and 20+ columns from it then realistically the data should be dumped into a real database because <rant> EXCEL IS NOT A DATABASE APPLICATION!</rant>

                • 5. Re: When To Use Which Connection (Live vs Extract)
                  John Sobczak

                  You can also publish your extracts and re-use them across workbooks which will help reduce server extract clutter.

                  • 6. Re: When To Use Which Connection (Live vs Extract)
                    Kamal Tanwar

                    Maybe a too late response but in case if you're still hanging in there, suppose I have a humongous dataset would it still be ideal to use an extract? Since it's in-memory (which I assume means using RAM or similar hardware) data, I thought it might slow down the machine.

                    • 7. Re: When To Use Which Connection (Live vs Extract)
                      Toby Erkson

                      Kamal Tanwar ,

                      Try the data source Live and as an Extract and see which performs best


                      If it's an extract I'm confident that it will be faster.  Data that is in-memory will process much more quickly due to the way Tableau basically organizes it AND, well, RAM is going to always be faster than a hard drive.  You want the data in-memory!  This is why it's important for workbook authors and the Tableau Server to have lots of RAM.  I recommend 12GB RAM minimum for my end users on their laptops.

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