Re: XMLDocument (SQL/XML X030)

so 25. 1. 2025 v 15:10 odesílatel Chapman Flack <jcflack(at)acm(dot)org> napsal:

> On 01/25/25 02:16, Pavel Stehule wrote:
> > because the function does nothing, then it is useless to convert input to
> > XML and force detosting
> >
> > Maybe the body of the function should be just
> > ...
> > PG_RETURN_DATUM(PG_GETARG_DATUM(0));
>
> That sort of motivated my question upthread about whether there is
> already a function somewhere in the codebase that does exactly that
> and could be named in the pg_proc entry for xmldocument, as an
> alternative to supplying a brand-new one.
>

this should not be a problem, because the already created function
XMLDOCUMENT surely will not be in the pg_catalog schema.

>
> Maybe this is the only instance where it turns out that 'identity'
> is the right behavior for a function. But if it could conceivably
> happen again, a single C function (maybe even named identity) could
> reduce code duplication and make quite clear what the behavior is
> with a \sf.
>

I didn't find any function like this.

Regards

Pavel

>
> A generic 'identity' function would be lacking the #ifdef USE_LIBXML
> and the error message, but I'm not convinced those matter here
> anyway. Without XML support, you'll already have raised that error
> in any attempt to construct a non-null XML argument to pass, and if
> you're passing NULL and the function is strict, you'll never see
> the error message from here anyway.
>
> Regards,
> -Chap
>
>