Re: BUG #19487: Error while executing SQL query involving XML parsing

сб, 29 авг. 2026 г. в 00:49, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:

> Andrey Rachitskiy <pl0h0yp1(at)gmail(dot)com> writes:
> > # Proposal Fix
> > Fold constant `XmlExpr` in `eval_const_expressions` (same path as
> > `MinMaxExpr` / `ArrayExpr`), so `IS DOCUMENT` becomes a boolean Const and
> > CASE drops the unused arm before simplifying `xpath()`.
>
> I don't object to simplifying XmlExpr where possible, but this patch
> appears to believe that every variant of XmlExpr is immutable.
> This is demonstrably false, eg
>
> regression=# set timezone = 'America/New_York';
> SET
> regression=# SELECT xmlforest('2026-08-28 12:00 UTC'::timestamptz AS foo);
> xmlforest
> --------------------------------------
> <foo>2026-08-28T08:00:00-04:00</foo>
> (1 row)
>
> regression=# set timezone = 'America/Chicago';
> SET
> regression=# SELECT xmlforest('2026-08-28 12:00 UTC'::timestamptz AS foo);
> xmlforest
> --------------------------------------
> <foo>2026-08-28T07:00:00-05:00</foo>
> (1 row)
>
> So you need to take a closer look at which variants can be promised to
> be immutable.
>
>
> Dear Tom,

Thanks for the review. I'll study it in more detail and come back with
corrections.

--
Regards,
Rachitskiy Andrey