Re: user defined XML aggregate not working as (i think) it should

Thanks Tom,

That was indeed the issue.

Regards,

Rhys

On Wed, Oct 3, 2012 at 8:58 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Rhys A.D. Stewart" <rhys.stewart@gmail.com> writes:
>> I have an xml aggregate function that  always returns 'ERROR:  invalid
>> XML content'. However an identical function that uses text produces
>> valid xml with the same inputs.
>
> I believe the reason this doesn't work is that the aggregate's initial
> value is faulty: it's supposed to be an XML value and it isn't.
>
> regression=# select ''::xml;
> ERROR:  invalid XML content
> LINE 1: select ''::xml;
>                ^
>
> It's unfortunate that the CREATE AGGREGATE command doesn't complain
> about that --- maybe we could improve it.
>
> As far as making a working aggregate goes, I'd try leaving off the
> initcond clause (so that the initial value is NULL) and then marking
> the transition function STRICT.  (plays around with xmlconcat on
> nulls ...) hm, maybe you'd not even need the STRICT marking, though
> personally I'd suggest it.
>
>                         regards, tom lane