October 24, 2011 at 12:55 am
I've a question about the following schema:
Type (dim) -> FactA
FactA DD (dim) -> FactA
Date (dim)-> FactA
FactA DD (dim) -> FactB
Date (dim)-> FactB
FactA = eg Order
FactB = eg. orderlines
FactA DD dimension is a Factdimension of FactA en i've a FK column in FactB to this FactA DD dimension (in the dimension usage tab).
What if i want to select (filter) with the Type dimension records in FactB? As i know now the same value is shown when browsing the cube. Is it possible to filter some records from the Type dimension and show only the relation records of FactB? Or should i include the Type dimension in FactB also? This doesn't seems a good solution to me..
Hennie
October 25, 2011 at 4:15 am
You seem to be describing fact tables that can be construed as parent child. If that's the case, most, if not all or nearly all, dimensions that can be associated with the parent can be associated with the child, but not vice versa. If having the Type works in the parent fact table and it would be useful to also have it associated with the child fact table, then include it there. The main issue is that if your rows are updatable, you have to keep the items in sync.
October 25, 2011 at 4:35 am
Hi,
Yes, there is a parent child relation between the fact tables. Okay you're saying: add the dimensions of the parent fact to the child fact?! Hmmm for clarity, purity, etc i didn't want to do this but it seems a option i could go for.
Hennie
October 25, 2011 at 4:41 am
I'm not sure what purity has to do with it. If there's a business need for it, then it's our job as data organizers and providers to make that data available if it exists. Cubes have major downside, they can only deal with one level of granularity, so sometimes you have to provide dimensions at lower levels that seem to belong to upper levels.
October 25, 2011 at 5:15 am
Well, off course you have a point and in this case i could build this as you suggests but my question has also a fundamental background: whenever i want to select a fact with a dimension that belongs to another fact i have a problem, right?
And perhaps your remark: "Cubes have major downside, they can only deal with one level of granularity" answers a part of this question.
Yet again, it seems so stupid that this can't be done.
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