Re: Segfault in RI UPDATE CASCADE on partitioned tables with LIKE+ATTACH child (attnum drift)

On Fri, Oct 17, 2025 at 6:08 PM David Rowley <dgrowleyml@gmail.com> wrote:
> On Fri, 17 Oct 2025 at 14:21, David Rowley <dgrowleyml@gmail.com> wrote:
> > Thanks for the detailed report. It seems to have been caused by
> > ba9a7e3921. For some reason the ResultRelInfo.ri_RootResultRelInfo
> > isn't set for this partition which causes ExecGetChildToRootMap() to
> > think no translation is required.
>
> The problem is with the ResultRelInfo caching that's in
> ExecGetTriggerResultRel(). The code there tries looking into the
> estate's es_opened_result_relations, es_tuple_routing_result_relations
> and es_trig_target_relations Lists to see if the ResultRelInfo was
> created before. In the problem case the ResultRelInfo is found in
> es_trig_target_relations and unfortunately it's been set up by some
> code in afterTriggerInvokeEvents() which passes a NULL rootRelInfo.
> This means when ExecGetTriggerResultRel() is called again this time
> passing the correct rootRelInfo, the cached one that has the NULL
> ri_RootResultRelInfo is found and returned.
>
> This results in the ExecGetChildToRootMap() code doing the wrong thing
> because it sees a NULL ri_RootResultRelInfo therefore does not
> translate the slot into the slow format of the partitioned table.
>
> I've attached a patch which fixes the problem. I'm just not sure if
> it's the right fix for the problem. I suspect the real problem is down
> to the fact that ExecGetTriggerResultRel() passes a NULL rootRelInfo
> in the first place. I just don't see a good way to figure out what the
> parent table should be so we know to create a parent ResultRelInfo as
> the trigger that is firing is for the partition, not the partitioned
> table. I don't see any way to figure out that the trigger is being
> fired because it's cascading an update of its parent partitioned
> table... At a guess, it feels like there might be some fields missing
> in AfterTriggerShared to figure this out.
>
> Any thoughts on this Amit?

Thanks for the off-list heads-up, David.

I'll need to play around with Dmitry's test case a bit before I can be
sure, but I agree with your suspicion -- something's not right if a
result rel without a root rel set ends up in a path where tuple
conversion matters.

--
Thanks, Amit Langote