Constraints on Dimensions

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Constraints on Dimensions

Post  tropically on Tue Jun 22, 2010 2:38 pm

Hi
I had a quick question on constraints on the dimensional tables. I have several column, ex active_flag (just an example ) whose valid values are Y or N. The dilemma is whether I should leave the constraints in the dimensional tables, or move it to the ETL process. I'm almost sure that I read it somewhere that the ETL should be handling the scenario, but need someone to re-assure me on this.

Thanks for you help.

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Re: Constraints on Dimensions

Post  ngalemmo on Tue Jun 22, 2010 3:53 pm

I'm not sure what you mean by 'moving it to the ETL process'. If you mean, for example, to exclude inactive rows from the dimension table, then I would say no... The problem you run into is if you are loading historical facts, you may not have a dimension row to reference in the fact table. You always want facts to reference a dimension row, if it so happens that that particular dimension value is no longer used, so be it. Leave those attributes in the dimension table.
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Re: Constraints on Dimensions

Post  BoxesAndLines on Tue Jun 22, 2010 4:25 pm

Leave them off. It slows down the load process.
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Re: Constraints on Dimensions

Post  sgudavalli on Wed Jun 23, 2010 3:00 am

If it is a constraint for your dimension table then you dont need it in you warehouse. Take it off....

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