4 Replies Latest reply on Jun 27, 2019 4:45 PM by Lauren Bearden

# Normal function vs Window Function

Hi All ,

I am confused with normal function vs window function eg.

Avg(sales) vs window_Avg (sum(sales )) or window_Avg( sum(sales ),-2,0))

Can you guys please explain ..when we should decide whether to use normal function() or window_fuction (),eg Avg(sales) vs window_Avg(sum(sales))

Thank you

regards ,

Rahul

• ###### 1. Re: Normal function vs Window Function

Hi Rahul,

A regular aggregation (like sum or average) will take the aggregation of all the rows in your data source. If you have 3 rows, Tableau will simply take the average of those 3 rows.

Now, let's say you have a more advanced problem. You want to find the average of the sum of certain categories (2 pass aggregation, or an aggregation based on an aggregate). This is where you could use a function like WINDOW_AVG. The window functions will take into account only what's in the view, and aggregate based on those number. This comes in handy when you have something like the sum of sales for a certain dimension, but then want to find the average sales across the dimension. You could use a WINDOW_AVG.

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• ###### 2. Re: Normal function vs Window Function

Hi Rahul,

In addition to Lauren's response I just wanted to clarify her point of: "will take the aggregation of all the rows in your data source"  This means your filtered data-source so if you have specific calculations or filtering in place, then the regular aggregation will run against the final filtered set.

Steve

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• ###### 3. Re: Normal function vs Window Function

Thank you Michael ...it helped to understand .

On Thu, Feb 11, 2016 at 6:36 PM, Michael Hesser <