RE: Large databases

Not just space savings. Redundant data is hard to update correctly, hard to ensure that it is entered the same way in more than one place, hard to ensure that referential integrity has been applied etc. All of those reasons still apply. Datawarehouses slip by based on the fact that they do little or no data changes. Denormalize a data with a lot of editing and after a short while your database will not return a correct answer depending on the phrasing of the questions.

Allan

-----Original Message-----
Sent: Wednesday, April 16, 2003 4:55 PM
To: Multiple recipients of list ORACLE-L

I think the thing that maybe hasn't been stated is that "normalization" of data was developed because..... storage space was extremely expensive. Eliminating redundant data was THE driving factor in data modeling. In a typical system you could save tens of thousands if not 100K if you could eliminate redundant data. Speed and performance was not as important as data integrity and cost. In those days...many "users" were not "users" until these systems were created. They went from a paper world to a green screen and they rejoiced and said it was good.

Now we want real time access, instant queries against huge production databases that store millions of rows of data on the price change of a bunch of nuts sitting in a bin halfway across the world.

The users now feel the need for accessibility and performance as storage is cheap...they want the data. So design for speed and accessibility and to deliver the data without bringing down the database with big ugly nasty adhoc queries.

Brad O.

"I want a goose that lays golden eggs daddy...and I want it now!" Veruka - WW&CF

-----Original Message-----
Sent: Wednesday, April 16, 2003 3:55 PM
To: Multiple recipients of list ORACLE-L

>
> Question to all you practical DBA's out there: Is is slower or faster
> to normalize or not?

>From an Oracle tuning book (I don't recall the title, but it was from
Oracle
Press):

"Store the data the way you intend to query the data."

(I might add: "if possible")

There was also a quote, the gist of which (I don't recall it exactly), was something like: No large, fully normalized database can perform worth diddly.

(Maybe a little extreme, but probably as a reaction to those who insist that all databases MUST be fully normalized.)

I don't debate this kind of stuff, since it is religion. But, if you are counting votes, I tend to agree.

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