Question

Compare and contrast the 3 types of facts tables: Additive, Semi-Additive, and Non-Additive.

Answer 1

ADDITIVE:- Those facts that can be added across all the dimensions of the fact table.All the mathematical calculations can be performed across all the dimesions .It is the numeric value in the Fact table that has more flexiblity e:g Total sales of a company, can be added across various dimensions customer dimension , location etc. also we can add sales hourly in order to obtain the daily sales, weekly, monthly, quarterly or yearly sales.

NON-ADDITIVE:- those facts that cannot be added across any of the dimensions present in fact table. So these facts should not be stored within the fact Table ,as these are manipulated on the additive facts within the fact table.E:g Account balance ,Inventory Level, dealing with discount percentage like someone say that the total discount percentage is 1200% (makes no sense) in the mall.

SEMI-ADDITIVE :- those facts that can be added across some certain dimensions but not through all of them.

E:g Account Balances, for the same customer we can’t add up Account balances for the duration of time as it is the latest amount at some point of time.

Also If we have to add the account Balances of 10 customers, we can add it.

Also Percentage and Ratios are stored like Numerator and Denominator.

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