A semi additive fact is one where the measure can either have only a subset of aggregations applied to it, it you can count the measures but not sum them, or the measures are only additive over a subset of the dimensions.
Using our "daily_balances" fact above would be a good example of a semi additive fact. The daily balances can be aggregated by customer if the customer has multiple accounts to give the customrs daily balance, however the balances could not be aggregated over time as adding last weeks balance onto this weeks balance would result in a nonsensical figure.
No comments:
Post a Comment