Modelling a new warehouse

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Modelling a new warehouse

Post  themitch on Fri Oct 18, 2013 12:20 pm


I'm new to all this and am just modelling my first star schema. Was just wondering about how people type columns in their dimension/fact tables - I was speaking to someone the other day and they set all their text fields to be Varchar2(255), all their number columns to be number, and all dates fields to be Date. That way, any upstream change didn't require model changes in the DW.

Is this typically what others do, too? Or do you explicitly type fields as required, ie using different string lengths, different number precisions, etc.?



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Re: Modelling a new warehouse

Post  ngalemmo on Fri Oct 18, 2013 2:10 pm

Depends on your database and BI tool. Some DB's will store time in DATE types, while others require using the TIMESTAMP type.

As far as VARCHAR goes, having everything at 255 can be a pain for users if the BI/reporting tool they are using sizes columns according to their declared size.

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