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Re: Pros and Cons of using Char and Varchar2

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Thu, 5 Apr 2001 22:55:06 +0200
Message-ID: <tcpsvrmbhggdc3@beta-news.demon.nl>

"Rene Nyffenegger" <rene.nyffenegger_at_gmx.ch> wrote in message news:Xns907AE5A9BBC65gnuegischgnueg_at_130.133.1.4...
> >Cost: when varchar columns are updated they may be starting the feared
> >chained rows menace.
>
>
> What is the 'feared chained rows menace'?
>
> Rene
>
>
>
> --
> Rene Nyffenegger
> rene dot nyffenegger at adp-gmbh dot ch
>
>

The menace is you need 2 I/Os to fetch 1 row. If your table has a substantial amount of chaining you will immediately notice that.
In order to prevent that one of the guidelines is of course the block size of your database should be bigger than your biggest rows. If you have 3k rows and 2k blocksize, you are just asking for trouble.

Hth,

Sybrand Bakker, Oracle DBA Received on Thu Apr 05 2001 - 15:55:06 CDT

Original text of this message

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