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Defining SCD Type at the record level

Posted: Thu Jun 02, 2005 7:42 am
by itcconsulting
I'm in the process of finalizing a dimension loading process following Kimball's methodology. I have a question that may change my process. What's the affect of treating the whole record as Type 1 or Type 2 instead of individual columns on a record?

Posted: Thu Jun 02, 2005 7:47 am
by diamondabhi
Welcome itcconsulting,
I think thats how it should be, can you be more specific with ur problem.

Thanks,
Abhi

Posted: Thu Jun 02, 2005 8:00 am
by itcconsulting
If my dimension table contains 4 non key attributes and one (or two) of those attributes require Type 2 SCD response, could I just treat any changed row as Type 2?

Posted: Thu Jun 02, 2005 8:26 am
by Sainath.Srinivasan
Yes. W.r.t. that one col.

Posted: Thu Jun 02, 2005 10:22 am
by itcconsulting
What's the downside of treating any change as a Type 2 regardless of the column?

Posted: Thu Jun 02, 2005 10:26 am
by Sainath.Srinivasan
You need to include complex conditions and more development time.

You landup with performance head-ache and development back-ache.

Again, everything depends upon your business requirement, analysis and design.

Posted: Thu Jun 02, 2005 3:18 pm
by itcconsulting
In speaking with the business community, I found that there is a business requirement to define the SCD Type at the field level. Could someone provided some advice on the DataStage logic needed make the field level SCD decision within my server job?

Posted: Thu Jun 02, 2005 3:21 pm
by Sainath.Srinivasan
Search this forum for more details.

Posted: Thu Jun 02, 2005 4:22 pm
by ray.wurlod
The DataStage logic is exactly the same as the "logical logic". If a field is a candidate for recording change, then a new record must be created whenever there is a change in that field. Therefore, you must determine whether a change has occurred. This involves being able to see (pre-load) what's already current in the target table, and to test for change in every candidate field.