Oracle-L: Re: data warehousing desing - to denormalize or not to denormalize

From: <Jared.Still_at_radisys.com>
Date: Fri, 10 May 2002 11:33:35 -0800
Message-ID: <F001.0045E8D9.20020510113335@fatcity.com>

One philosophy of DW states that you build a DW that is fairly normalized, much like an OLTP database, albeit one with a temporal component and complete logging of transactions within the data.

This is then used as a warehouse. The data from the DW is used to assemble data marts. These data marts are queried by users.

They never look at the data warehouse.

So to answer your question: It depends.

On how much time you have
do you want the ability to create new data marts without adding to the ETL system ? ( it should already be getting everything you need )

Since you already have something that looks like a DW, why not use that to build data marts that employ star schemas and bitmap indexes? They are easier to query, and faster.

I believe both Kimball and Inmon subscribe to this philosphy.

Jared

Gurelei <gurelei_at_yahoo.com>
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05/10/2002 11:43 AM
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        Subject:        data warehousing desing - to denormalize or not to denormalize - that is

the question

Hi.

We are designing a small database using a data warehousing desing. We have created a 3rd normal form and are now debating whether and how to denormalize it. I see the pluses of denormalization - easier queries creation and tuning. What are the disadvantages that we should be aware of? Wasted space is not an issue because the tables a pretty small. What else should we consider as a potential issue?

thank you

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Re: data warehousing desing - to denormalize or not to denormalize - that