1 Reply Latest reply: Dec 30, 2014 10:14 AM by Manish Kachhia RSS

    what is subset ratio

      hi guys what is sub set ratio  with examples

        • Re: what is subset ratio
          Manish Kachhia

          Information density of the field, which indicates the percentage of rows that contain a non-null value

           

          Subset ratio, which shows the percentage of all distinct values for a field in the

          table compared to all the distinct values for that field in the entire data model. It is

          only relevant for key fields since they are present in multiple tables and do not all

          share the same value.

          Subset ratios can be used to easily spot problems in key field

          associations.

               For example, when the combined total of subset ratios for multiple

          tables is 100 percent, this may indicate that there are no matching keys between

          these tables.

           

          REF: QlikView 11 For Developers..


          Let me give you simple example


          Sales:

          Load * Inline

          [

            Customer, Sales

            A, 100

            B, 200

            D, 300

          ];

           

          Customer:

          Load * Inline

          [

            Customer

            A

            B

            C

            D

          ];

           

          If you write above sample script and will check the Table (CTRL + T), you will find two tables.

          Sales and Customers


          On Sales Table, if you hover the mouse on Customer field, you can see the Subset Ratio is 75% because there is not sales data for Customer C.

           

          Now if you change the script for table Customer like below..

          Customer:

          Load * Inline

          [

            Customer

            A

            B

            C

            D

          ]

          Where Exists (Customer);

           

          If will not load the Customer C as there are no sales data for the same.

          Now check the Subset Ratio. It will be 100%.

           

          If subset ratio is less than 100%, the key is called as Primary Key

          but for 100% it is called as Perfect Key.