Re: Weird behavior with custom operators

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От Matthieu HUIN
Тема Re: Weird behavior with custom operators
Дата
Msg-id 1282836194.2536.28.camel@mhu.ifr.lan
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Ответ на Re: Weird behavior with custom operators  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
Hello Tom,

Thanks for the answer. I think this is exactly what's happening here.
What I cannot understand though, is why this specific error isn't thrown
when using the others operators I defined that have the same kind of
operands.

About your last question; I created this datatype so that I could store
values as text and compare them to floats easily if they can be
converted into a numeric type (since numeric order differs from
alphanumeric order). I used to call CASTs in my queries when needed, but
I realized that doing so made my various existing indexes useless. And
since I'd rather not create a specific table for numeric values, this is
what I came up with.

I have very little experience with postgresql or databases in general so
any advice on that will be gladly taken.

You are suggesting to use a domain : would I be able to extend operators
that way ?

Le jeudi 26 août 2010 à 11:05 -0400, Tom Lane a écrit :
> Matthieu HUIN <matthieu.huin@wallix.com> writes:
> > xxx=> SELECT value FROM tags WHERE value > 3 LIMIT 1;
> > ERROR:  unsupported type: 17886
>
> I think you're probably hitting this:
>
>     /*
>      * Can't get here unless someone tries to use scalarltsel/scalargtsel on
>      * an operator with one numeric and one non-numeric operand.
>      */
>     elog(ERROR, "unsupported type: %u", typid);
>
> While you could possibly make it work by writing wrappers around those
> selectivity functions instead of using them directly, I'm kind of
> wondering what is the point of this datatype anyway?  Seems like
> declaring it as a domain over text might be easier.
>
>             regards, tom lane



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