1 Reply Latest reply on Sep 30, 2013 8:46 AM by Russell Christopher

    How are multiple tables in an extract related in Firebird

    Robert Sutter

      When Tableau extracts the data from something like a star-schema where joins are necessary, is the data still stored in a relational format in Firebird or is it stored as one table; something like a flat data set?

       

      The reason I'm asking is because for non-extract queries where there are tons of records, it sometimes appears to be faster to have Tableau connect to a flat table instead of joining a base table with lots of keys to many dimensions.

       

      A lot of the data we're generating for other applications is in these flat non-dimension tables and I'm wondering of it makes sense to have it dimensionalized if Tableau would store the data that way and use it that way making the vis's run faster once published.

        • 1. Re: How are multiple tables in an extract related in Firebird
          Russell Christopher

          Hey Robert -

           

          When data is extracted, it is extracted as "a big flat table" - querying it is more efficient that way.

           

          We also don't store that stuff in Firebird - we built/use a completely different in-memory technology for Extracts. Firebird is still used a little bit in the product, though - mostly for geocoding work.

           

          (Very) generally, you'll find that the fewer joins you need to traverse in your database, the faster it can return results to you. So, OLTP/Snowflakes often give you the worse performance, stars give you pretty good perf, and highly de-normalized gives you the best.

           

          Hope this helps!