Question

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-O and as directed by the first commenter, now posted this question here.)

No correct solution

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