3 Replies Latest reply: Nov 8, 2017 7:13 AM by Jonathan Dienst RSS

    What is Faster, a Sum or a Max

    Eric Vilarrasa Canadell

      Hello, I have a question about optimisation.


      Suppose that my table have binary data on a dimension (0 or 1) named "IsConnected" that is telling that if someday a product is or is (1) not (0) connected, every day. If you select a period of some days (maybe it depends on the size of days you select, let's suppose that is huge) what is better to do in order to improve the efficiency of the formula:


      1. Sum(IsConnected)
      2. Max(IsConnected)


      Since it is a relational DB, I think it is easier to do a Max because QlikView have a Inner Table with the different values of the dimensions so it has only to check between two values.


      The second question (less important for me now) and maybe more tricky is: What if the variable is not binary?


      For example: Suppose that we have the number of Connected Hours of a product, in one column we have the accumualated of the connected ours ("Accum_Conected_Hours") and on the other the ours that this product has been connected this day (Daily_Conected_Hours) . What it's better in order to calculate the total hours that the product has been connected on a given period:


      1. Sum(Daily_Conected_Hours)
      2. Max(Accum_Conected_Hours) - Min (Accum_Conected_Hours) *


      * I am aware that doing a max - min may be the result is not the same but it can be fixed with a set analysis.



      Dummy data: