>Besides, in database theory you don't store sums in any table.

Many database applications store snapshot tables with aggregations.

As an example, when I worked in WIC, we created snapshot tables at the end of the month to store a picture of participation, plus tallies/sums of children, infants, and women on the program by county. Big help for historical reporting.

In many accounting applications, end of month/period snapshot tables are generated as part of end of period lockdown procedures. The numbers you see on a P&L (gross dollars, costs, spending, net revenue, net profit, etc.) are likely stored as aggregations in the snapshot table. Again, big help for historical reporting.