As an example, let's say I have a fact table with two dimensions and one measure
FactMoney table
ProjectKey int
PersonKey int
CashAmount money
The two dimensions are defined like this:
DimProject (a type 0 dimension - i.e. static)
ProjectKey int
ProjectName varchar(50)
DimPerson (a type 2 slowly changing dimension)
PersonKey int
PersonNaturalKey int
PersonName varchar(50)
EffectiveStartDate datetime
EffectiveEndDate datetime
IsCurrent bit
Pretty straightforward so far. Now I'll introduce a Person Category concept.
DimCategory
CategoryKey int
CategoryName varchar(50)
And build an M2M relationship between DimPerson and DimCategory
BridgePersonCategory
PersonKey int
CategoryKey int
So - people can have 1..n categories.
My problem is - as Person is a slowly changing dimension, when a person's name changes, we add a new person row and update our effective dates and is current flags, no big deal.
But what do we do with the person's categories? Do we need to add more rows to the bridge table every time a new person version pops up?
And as a corollary, if a person's categories change, does that mean we need to create a new row in the person table?
(please note I've also asked this question at stack-Ostack-O and as directed by the first commenter, now posted this question here.)
