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jeffc avatar image
jeffc asked

demoralization

I am a college student studying database and one of my projects is demoralization of database
homeworknormalizationnormal-form
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So, forgive me, what's your question? And you probably mean "denormalization" rather than "demoralization". Not sure you can undermine the morality of the database. ;-)
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I just want to thank every one for your feed back. I get more from this than my classmates online. if any one has ?s for me i will do the best i can to answer them. again thank you.
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Sorry about miss print on denormalization
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Miss Print won't mind, she's used to that!
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@JohnM you mean "morale", not "morality", surely? ;-)
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tanglesoft avatar image
tanglesoft answered
Normalisation is the process of removing redundancy, duplication and dependency in fields and tables in the database. However if all levels of the normalisation are applied to the letter this often results in an inefficient database model. The database model will often come about from either a logical design model or these days quite often from an object model that needs database persistence. Once the initial physical model is drafted you then need to look at the typical operations that apply to the model. Such as get customer, save customer, get customer orders etc. If you find that in order to get something simple like a customer requires 10 tables to joined it's a sign that it is over normalised and will perform poorly. In this the de-normalisation process either merges tables or deliberately duplicates data to get results in timely fashion.
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tanglesoft avatar image
tanglesoft answered
Some of the databases designs I have seen have been immoral.
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Lack of documentation - that's immoral, and demoralizes me when I have to support it...
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Valentino Vranken avatar image
Valentino Vranken answered
Database denormalization is also used in the context of data warehousing. Often the normalized OLTP model will get denormalized into a star schema with Fact and Dimension tables. This type of model makes reports run faster due to less joins. Data duplication is no longer a concern in a DWH. See also [Denormalization (Wikipedia)][1] and [Lesson 3: Optimizing the Database Design by Denormalizing (TechNet)][2] [1]: http://en.wikipedia.org/wiki/Denormalization [2]: http://technet.microsoft.com/en-us/library/cc505841.aspx
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Well, that depends on how you look at it I guess. When compared to having all data in one flat table, the dimensional model is indeed normalized more. On the other hand, when compared to a 3NF OLTP model, it is less normalized thus possibly denormalized?
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I don't know that I would call a star schema denormalized. It's a different design, not a badly normalized design.
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Agreed. It's absolutely not normalized from a third normal form perspective. But it's not supposed to be. A true star or snowflake schema is it's own critter and separated from the rules of normalization.
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Are you saying that snowflakes are special? ;-)
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I'm saying that YOU are a special snowflake. Almost the same thing.
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