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Home -> Community -> Usenet -> c.d.o.server -> Re: Key Columns: char vs. number
Nuno Souto wrote:
>
> This "number better than char for key" thing unfortunately made
> the rounds a few years ago. Some "experts" who consider
> that all tables must have a numeric PK and other such pearls of wisdom
> were given too much importance. Probably their DB2 background
> made them into "ORACLE experts", although I still fail to see why that
> should be so...
>
> As a result, there is a crop of people around who
> think these things are in any way true.
>
> There is no such thing as numeric fields being better for PK
> or indexes than char or varchar. Each case has to be examined
> and the required data type used for PK or index, that's all.
>
> BTW, number types are not necessarily fixed length. If you define
> them as NUMBER(n) with "n" being the precision you want, they do
> NOT take up 22 bytes! There was an old version of ORACLE where
> any column defined as NUMBER (without the precision) would always
> take 22 bytes, but I believe that has been fixed. Nowadays, number
> columns are variable length as is the length of a number value.
> Check out the "book" on section data types.
>
> --
> Cheers
> Nuno Souto
> nsouto_at_nsw.bigpond.net.au.nospam
> Is there a nospam domain?
> http://www.users.bigpond.net.au/the_Den
> Jens Mayer <jmayer_at_ratundtat.com> wrote in message
> news:3771df06.6172285_at_news.space.net...
> > Hi folks,
> >
> > yesterday I had a discussion with an Oracle-experienced friend about
> > the question: is ist better to use CHAR or NUMBER datatypes in Key
> > Columns, eg. in a Primary Key ?
> >
> > Until now I thought that it's better to use CHAR, because NUMBER
> > takes 22 Bytes of Space in each case. My friend mentioned, that using
> > NUMBER in Key Columns makes better performance.
> >
> > Who is right ?
It makes no difference what precision you specify to the amount of storage used for a number....
Of course, its still important to have the precision for validation
reasons etc etc etc
--
"Some days you're the pigeon, and some days you're the statue." Received on Thu Jun 24 1999 - 08:52:53 CDT
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