>From what I remember, one of the main advantages of a normalized database is a certain level of data integrity and flexibility. The integrity comes from foreign keys, lack of duplicate data, and generally a data design based on characteristics of the data. The flexibility comes from the ablility to query in many different ways (you are not restricted as you are in a heirarchical db). Though I have never designed a data warehouse, I always thought that the integrety piece would be less of an issue. Since there are very few writes to a warehouse, there is less chance to fowl up the data integrity as long as there are good controls on the load. Flexibility on querying a warehouse seems to also be possible using other design methods (fact tables, snowflake, ...)
Henry ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Friday, May 10, 2002 3:48 PM > Let's see . . . disadvantages . . . hmmm. scorn of anyone that understands > data warehousing? On your resume putting "created a completely normalized > DW" and wondering why everyone giggles when they read it. > > Actually, a normalized schema will probably use less space than > denormalized. > The key point is your users. A typical normalized design means a lot of > tables. These tables must be joined in specific manners. Non-I.S. users find > this intimidating. So they don't use it. So you've spent a lot of time > creating a DW only to have nobody use it. > Normalized schemas are optimized for inserts and updates, not > generating reports. To generate a report from an OLTP normalized schema, you > usually start by interviewing the developers. And they usually have to do > some research. A DW is a "write mostly" schema. Our DW is only refreshed > weekly. Sunday is spent loading it and Monday the users charge in and run > reports all day. > Study star schema. Go to http://www.ralphkimball.com and read > articles he has written, starting with the oldest ones and working forward. > Read Ralph Kimball's book "The Data Warehouse Toolkit: Practical Techniques > for Building Dimensional Data Warehouses". Classic work, excellent starting > point. > A beginning star schema DW should have only a central fact table and > 4-6 dimension tables. Non-computer-geeks actually have a hope of > understanding how to navigate that. How many tables did your 3nf schema > produce? > Or go ahead, build a normalized one, then study and build the second > version incorporating the hard-won lessons others have learned. > Dennis Williams > DBA > Lifetouch, Inc. > [EMAIL PROTECTED] > > > > -----Original Message----- > Sent: Friday, May 10, 2002 1:43 PM > To: Multiple recipients of list ORACLE-L > - 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 > > __________________________________________________ > Do You Yahoo!? > Yahoo! Shopping - Mother's Day is May 12th! > http://shopping.yahoo.com > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Gurelei > INET: [EMAIL PROTECTED] > > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 > San Diego, California -- Public Internet access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: DENNIS WILLIAMS > INET: [EMAIL PROTECTED] > > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 > San Diego, California -- Public Internet access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Henry Poras INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
