Re: BUG #18986: SIGSEGV in nodeModifyTable.c during Parallel Execution

On Wed, 16 Jul 2025 at 10:55, Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> The problem, however, is that GetTupleForTrigger() tests for MERGE by doing
>
>     if (estate->es_plannedstmt->commandType != CMD_MERGE)
>
> which doesn't work if the MERGE is inside a CTE. So we need a
> different way for ExecBRUpdateTriggers() / GetTupleForTrigger() to
> know that it's being called from within a MERGE.

Attached is a reproducer using the merge-match-recheck isolation test.

I believe that the bug only goes back to v17, because MERGE could not
appear inside a CTE prior to that.

I think that best thing to do is pass the commandType to
ExecBRUpdateTriggers(), except that in v17 we shouldn't change the
signature of ExecBRUpdateTriggers(), so a wrapper function will be
needed, similar to what 9321c79 did.

Question: Is it OK to change the signature of ExecBRUpdateTriggers() in v18?

Regards,
Dean