The Spider Schema is an interesting approach to the distinct count performance issue with Analysis Services, and modelling data in general. It is an approach to fix some of the flaws with star schema design. It adds an intermediate table between dimension tables and fact tables, which house the unique key combinations for dimensions in the fact.
It sounds a bit like the Data Vault architecture promoted by Dan Linstedt, though targeted at reporting on vs vaulting the data.
More details here.
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