By default, each and every filter in Tableau will access all the records in our data source without taking into consideration the other filters. It means that these filters are computed independently of each other. However, we may want to set one or more categorical filter as context filters for the view.
For example, we have a Filter/Set, which gives us the Top five customers by Sales. Now this Set gives us the Top 5 customers from the entire data set. However, when we get another filter, let's say Region, then we expect Tableau to give us the Top five customers for the selected Region. But, because these filters are independent, Tableau still gives us the Top five customers from the entire data set and if it doesn't find a record of any customer from the Top five list in a particular region, then it will simply remove that name from the list. This is because Tableau doesn't understand that the Top five Filter/Set needs to be based on the output of Region...
