Re: PG19 FK fast path: OOB write and missed FK checks during batched

On Wed, Aug 19, 2026 at 10:12 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> On Wed, Aug 19, 2026 at 12:09 AM Noah Misch <noah(at)leadboat(dot)com> wrote:
> > On Tue, Aug 18, 2026 at 10:42:14PM +0900, Amit Langote wrote:
> > > After considering Peter's report of another bug [1] that is fixed by
> > > 0001, I tested both his reproducer and nested firing involving the
> > > same constraint.
> > >
> > > The latter exposed a problem in v1: the cache was still keyed only by
> > > constraint OID, so a nested check of the same constraint reused the
> > > outer entry and did not register a callback at the nested query depth.
> > > In v2, the key is now (constraint OID, query depth), giving each
> > > firing level its own entry and callback.
> > >
> > > 0001 now includes regression tests for both cases. 0002 and 0003 are unchanged.
> > >
> > > I would like to commit these sometime this week and would appreciate a review.
> >
> > I won't be able to review this. The list should consider it up for grabs.
>
> Attached is v3, rebased over latest master.
>
> I reorganized the series to separate firing-state restoration (0001),
> per-firing-cycle batch and callback scoping that fixes Peter's report
> [1] (0002), and per-subtransaction batch tracking as suggested by Noah
> (0003). 0003 also folds in the invariant assertion previously sent
> separately. The combined code is otherwise unchanged from v2.
>
> [1] https://postgr.es/m/CAH2-Wz%3DD533JbF_ak_Pc8kP0FKse-ju8DnMxtjvY%3D%3DyHsP4xgw%40mail.gmail.com

I've now pushed 0001 and 0002. Since they fix live bugs, I decided to
commit them sooner rather than later.

I plan to commit the attached remaining patch tomorrow, barring
objections, and then close this item.

--
Thanks, Amit Langote