Re: BUG #17792: MERGE uses uninitialized pointer and crashes when target tuple is updated concurrently

On Tue, 14 Feb 2023 at 11:29, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
> I'm not sure that the location of the initialization is best. My first
> impulse was to add it in line 3618, with the "Set global context" lines;
> but then I think it's possible for one tuple of a partition to be routed
> correctly and a later one that is concurrently updated suffer from an
> improper value in cpUpdateRetrySlot.
>

Hmm, shouldn't it be initialised in ExecMergeMatched(), before line
2896, making the CMD_DELETE case match the CMD_UPDATE case? Otherwise
maybe an update action could be matched initially, try a
cross-partition update, setting cpUpdateRetrySlot due to a concurrent
update, and then upon retrying, a delete action might match.

Regards,
Dean