If I have multiple sheets/charts that use a common expression, is it more efficient to assign that expression to a variable and then reference the variable in the various sheets/charts than to have the expression repeated over and over in each object?
For example if I need to plot:
sum(bad_call)/sum(call_count) vs sum(good_call)/sum(call_count)
would it be better to create vCallCount =sum(call_count) and then plot
sum(bad_call)/vCallCount vs sum(good_call)/vCallCount.
Or is QlikView smart enough to recognize multiple instances of sum(call_count) and calculate it once?
It is easier to maintain if you use a variable. But that is the only advantage, because QlikView is smart enough - in both cases - to recognize multiple instances of the expression. The result will be saved in the cache and re-used for the other instances the same expression. (Given that the data scope is the same).