How to create surrogate key in dimension without unique value

Question

Hi, I have a dimension where there is no column with unique value. I want to add a surrogate key to replace the existing primary key which is derived from concatenating 3 columns(e.g. 'A'||'B'||'C'). I'm thinking of using sequence. But this won't allow me to link the dimension to fact table. How do I come up with surrogate key under this situation? Thanks. ~Tracy

Answer 1

I'm actually trying to accomplish something similar myself.
In my sources I've got two sorts of customers, ones that are directly reported, and ones whose information is provided with sales records (this is stored in module ODS).
Of course identification is different, but in the datamart (module DWH) I'm sort of forced to use an equivalent way of loading (due to the way it first used to work). To accelerate lookups on dimensions, I copy the ODS surrogate key to DWH dimensions, but this does not work for the 'inbuilt' customers because they do not have a surrogate key in the ODS.
They DO have means of unique identification, and at first I thought I could concatenate these (also 3) columns to use as identification code. Unfortunately this is VARCHAR2, where the surrogate key is (naturally) NUMBER.
So now it looks like I'm forced to first build a table in ODS especially for these 'inbuilt' customers and assign a surrogate key (by sequence) to it, this way it conforms to how 'normal' customers are loaded into DWH.
I guess you'll have to pull of the same trick, i.e. create a table with either only the 'translation' of D-code to a surrogate key or all information that is fed into the dimension, which then can be used as a lookup or as complete source when loading data into your datamart.
Good luck, Patrick