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From: Sybrand Bakker <postbus@sybrandb.demon.nl>
Newsgroups: comp.databases.oracle.server
Subject: Re: one big tables vs. many smaller
Date: Thu, 04 Apr 2002 19:18:52 +0200
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On Thu, 4 Apr 2002 16:00:59 +0200, "Steffen Ramlow" <s.ramlow@gmx.de>
wrote:

>what r the advantages / disadvantages of this?
>
>sample:
>
>Main (pk, id, c1, c2)
>Sub1 (pk1, fk1, c10, c11)
>Sub2 (pk2, fk2, c20, c21)
>
>rows:
>
>Main: 1,1,2,3
>Sub1: 1,1,4,5
>Sub2: 1,1,6,7
>
>vs.
>
>BigMain(pk,id,c1,c2,c10,c11,c20,c21)
>
>rows:
>
>1,1,2,3,4,5,null,null
>2,1,2,3,null,null,6,7
>
>
>the rows are always read as when Main and Subx would be inner joined
>
>obvious is, that BigMain has many null values (there are up to 10 sub
>tables) but u do not need to join Main and Subx
>
>i would use Main + Sub, coz it is better to maintain and to tune, but what
>about the costs of the join?
>
>both tables may contain millions of rows
>
>what r ur options?
>
>
Learn about normalization and denormalization.
Normalizing the data, provided you don't want to end up in hell,
should always have more priority than a few percent performance gain,
if any.


Regards

Sybrand Bakker, Senior Oracle DBA

To reply remove -verwijderdit from my e-mail address