Re: XMLDocument (SQL/XML X030)

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.

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.

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