0 Replies Latest reply: Feb 18, 2015 5:13 AM by Saverio Spadavecchia RSS

    Qvw file size behavior before and after dimension modification

    Saverio Spadavecchia

      Hi to all,

      i'm been studying "Qlikview Developer 11" and i noticed a curious thing in an exercise.

       

      There is a fact table and different dimensions. In several dimensions there are non-matching values with the fact table, then is suggested how delete this non-matching values from the dimensions to reduce the size of the qvw.


      To simplify i have loaded only one dimension (in addition of the fact table), before with non-matching values and after without.

      From an original dimension of about 55MB, after i have a qvw file of about 33MB.


      But, if i try to load only the fact table, the file size is about 54 MB.

      The question is ... how it is possibile?

       

      There is a compression of the data model only when i have loaded more than one table?

       

       

       

      Summary

       

      Size of file qvw loading one table at a time:

      54273 KB   Only fact table  (57 fileds x 1256075 records)

          255 KB   Dimension with non-matching values (2 fielsds x 6209 records)

          183 KB   Dimension without non-matching values (2 fields x 2142 records)

       

       

      54388 KB -  Fact table and dimension with non-matching values :

       

      Tables#Records#Fields#Keys
      Fact Table1256075571
      Dimension620921

       

       

      34901 KB - Fact table and dimension without non-matching values :

       

      Tables#Records#Fields#Keys
      Fact Table1256075571
      Dimension212421


      The records number of the fact table is the same, because QlikView perform a full outer join, then there isn't a subset of record for the fact table driven by the dimension filtered (in case of a inner join).



      For completeness, the fact table is loaded from a qvd, while the dimension from an access table.



      Can someone help me understand this behavior?


      Thank you all !!


      Saverio