In my extraction layer, I have a large data set (sales by Site, SKU & day). In most applications that I will be creating, I will need to show year over year comparisons. In apps where I will need to have sales by day, which are few and far between, I know that I can do a set analysis to create variables that show sales for the selected time period and the same time period last year. I expect that I could do this for data aggregated by week and month as well.
I have access to the fiscal calendar which has columns showing the date and the match date for the prior year, as shown below:
DATE
DATE_PY
12/31/2017
1/1/2017
1/1/2018
1/2/2017
1/2/2018
1/3/2017
1/3/2018
1/4/2017
1/4/2018
1/5/2017
1/5/2018
1/6/2017
1/6/2018
1/7/2017
From a system/app performance perspective, would it be better to use the set analysis or to add the sales from the prior year as another column in the transformation layer?
