Limitations of ER modelling while modelling a dwh

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Limitations of ER modelling while modelling a dwh

Post  bharadwaj.uma@gmail.com on Sun Jan 30, 2011 1:33 pm

Could anyone help me out of Limitations of ER modelling when used for modelling data in a dwh

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Re: Limitations of ER modelling while modelling a dwh

Post  BoxesAndLines on Sun Jan 30, 2011 3:18 pm

There are none I can think of.
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Re: Limitations of ER modelling while modelling a dwh

Post  ngalemmo on Mon Jan 31, 2011 4:48 pm

The downside is query performance. Those who subscribe to the Inmon approach to a data warehouse, that is, maintaing a somewhat 3NF data repository of all data, do not (or should not) allow end-user access to the repository for data analysis queries. There are two reasons for this: 1, the schema tends to be overly complex and difficult to use, and 2, massive queries run for a very long time. Inmon recommends that end-user accessible data be published in the form of data marts (usually dimensional, usually aggregate - star schema or cubes) or other data extracts for consumption.
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Re: Limitations of ER modelling while modelling a dwh

Post  BoxesAndLines on Wed Feb 02, 2011 12:00 pm

Ahh, when someone says ER-modeling, that doesn't imply dimensional or normalized data models.
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Re: Limitations of ER modelling while modelling a dwh

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