Re: ISN extension - wrong volatility level for isn_weak() function

Thanks, I did check that thread during my desperate attempts to figure this bug out.
In terms of the ergonomics of is_valid I think it’s actually quite nice. A GUC variable would be very nice - I kinda assumed the ISN module was create before GUC, hence the somewhat idiosyncratic is_weak(bool) session level setting.

However, cleaning things up to use GUC seems like it’d be bigger task, and also would only be an extra thing, as isn_weak function would need to stay in for backwards compatibility I assume.

In terms of just fixing the immediate bug, I believe it’d just be to change isn.sql line 3423 and 2433:

CREATE FUNCTION isn_weak()
	RETURNS boolean
	AS 'MODULE_PATHNAME', 'weak_input_status'
	LANGUAGE C
	IMMUTABLE STRICT <— should be VOLATILE STRICT
	PARALLEL RESTRICTED;

I believe even I could do this change, unless one of you pros would be open to doing it.
Am I right in understanding the next steps to do that would be to create a patch, and email it to pgsql-hackers? Or does that patch go here? Thanks

/Viktor
On 14 Mar 2025 at 15:14 +0000, Tom Lane <tgl@sss.pgh.pa.us>, wrote:
> Viktor Holmberg <v@viktorh.net> writes:
> > I haven’t checked the source code, but yes the isn_weak feature has some footgun potential. As it doesn’t respect transactions, but rather sets a flag on session level, it’s easy for the “isn weakness” to leak out into a connection pool.
>
> Yeah, really that ought to be a GUC I should think. There isn't
> anything well-designed about it ...
>
> I found some prior discussion here:
>
> https://www.postgresql.org/message-id/flat/C12AE0A2A752416C79F3EE81%40teje
>
> but we don't seem to have pulled the trigger on changing anything.
>
> regards, tom lane