[wdmmg-dev] Reading: Slowly changing dimensions

Wed Jun 29 14:53:58 UTC 2011

Hi,

Friedrich just mentioned issues with german classification system, that classifier IDs are reused. It is similar to reusing a telephone number. It is quite common problem in data warehousing. Here a little bit of reading for the topic and ways how the issue might be handled:

	http://en.wikipedia.org/wiki/Slowly_changing_dimension

Note (article related): naming convention: quite common practice is to call key from source with prefix or suffix 'code'.

In our case, for purpose of analytics, we use the Type 2 method for handling dimension change. We do that in transformation stage. This is another reason why surrogate keys for dimensions are being introduced.

Regards,

Stefan

senior business intelligence consultant
http://databrewery.org