Posted by Jeff Kish on 06/12/07 02:04

On Fri, 8 Jun 2007 21:07:04 +0000 (UTC), Erland Sommarskog
<esquel@sommarskog.se> wrote:

>Jeff Kish (kishjjrjj@charter.net) writes:
>> the data represents coordinates on images that can vary vastly in
>> scale and precision.
<snip>
>> one page might vary from -1.234565 to 1.3234343 in extents, placing
>> all coordinates in that range, and another might be a different type
>> of image and range from -10245 to 10245.
>
>Could you have coordinates that are 1E12 or 1E-12 as well? I would
>expect that is after all some practical limit. In this case you could use
>something like decimal(20,10). Or may be varchar is an alternative? I
>would definitely avoid float.
>
thanks.
so avoid float because it is a non exact storage and that makes it dubious for
part of a key, or is it just because floats are inherently bad in a pk for
performance reasons?
>Yet an alternative is some roll-your-own decimal. That is, you would
>save the coordinates as integer, and you would store the scale separately,
>possibly in a table with the page as key.
I really would like to/need to stay with some standarad / built in type.
I'll take a peed at the decimal... maybe I can make due with them.
why are they better than floats for the pk cols?
regards
Jeff
Jeff Kish

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