Home > ETL Best Practices > Slowly Changing Dimensions – No Worry

Slowly Changing Dimensions – No Worry

Our target system is not exactly a data warehouse. It’s a relational database, but not used as an operational system. I don’t want to call it pseudo data warehouse either, because it sounds so negative. I guess the best name for it is “Master Data Management” (MDM) system. With 20 different data sources to integrate, it deserves to be the “master” system.

Do we need to worry about the slowly changing dimensions as a typical data warehouse with a dimensional model should consider?

The answer is No based on this email from my supervisor.

From: Sherry
Sent: Monday, August 02, 2010 2:55 PM
To:
Subject: RE: Discovery Data

As I started to develop the daily incremental data loading process for the auto-discovery data, I realized that I have two high level questions to clarify first regarding the changes in dimensional data, specifically,

  • PC asset user
  • facilities where the PC is located
  • status changes in the PC assets
  • Operating system changes

If I understand it correctly, we will overwrite the above old data with new data for the PC assets if there are changes in them. In another word we will not track the change histories.

Sup***Correct, overwrite it or correct it based on the daily updates.  Your updates will come in two forms, brand new PCs that we don’t have in the database and need to add, and changes to existing PCs, as you defined above .

The second question to clarify is about data changes coming from data sources vs. data changes performed by user in Asset Manager client.

I am under the impression that the PC assets will be only modified through the back room of ETL process from the data sources, not through AM client.

Sup*** we are not going to block changes through the online AM client, but will always take the changes that come in through the daily ETL updates.  I am not worried about overwriting changes made through the AM client. 

Categories: ETL Best Practices
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