Re: pg_recvlogical: send final feedback on SIGINT/SIGTERM exit - Mailing list pgsql-hackers

On Mon, Jun 15, 2026 at 10:42 PM Ayush Tiwari
<ayushtiwari.slg01@gmail.com> wrote:
>
> Hi,
>
> On Fri, 29 May 2026 at 05:42, Fujii Masao <masao.fujii@gmail.com> wrote:
>>
>>
>> Currently, when pg_recvlogical exits due to SIGINT or SIGTERM, it can
>> terminate after writing decoded output locally but before sending feedback
>> that reflects the latest written position to the server. If pg_recvlogical
>> is restarted after that, the server-side logical replication slot may still
>> remain behind those already-written changes, and the same decoded data can
>> be sent again.
>>
>> Attached patch makes pg_recvlogical send final feedback once more during
>> SIGINT/SIGTERM exit, before sending CopyDone. That gives the server one more
>> chance to advance the slot far enough to avoid resending already-written
>> data after pg_recvlogical is restarted.
>
>
> Thanks for the patch!
>
> The problem statement and solution makes sense to me.
>
> I applied v1 and tried it locally.  It builds cleanly and the new block in
> 030_pg_recvlogical.pl passes.  As a sanity check I reverted just the
> prepareToTerminate() change and kept the test: the "does not duplicate decoded
> changes after signal shutdown" assertion then fails (the row is decoded twice
> on the restart), so the test is clearly exercising the fix too. I don't see any
> downside of having the fix attached.

Thanks for the review! I've pushed the patch.

Regards,

--
Fujii Masao