Re: Missing empty transaction optimization in pgoutput plugin

On Mon, Dec 8, 2025 at 12:19 PM Ashutosh Bapat
<ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
>
> test_decoding output plugin skips sending stream_start and stream_end
> if no change from a segment of a streamed transaction is sent
> downstream. If no change has been sent downstream across all the
> streamed segments it doesn't send commit or abort for that streamed
> transaction. But I don't see similar changes in stream related
> callbacks in pgoutput output plugin.
>
> While the changes discussed in thread [1] were committed, those didn't
> include this optimization for test_decoding plugin as well. The
> optimization was discussed in [2] separately as a bug fix. Maybe
> because it wasn't considered as an optimization that time, we may not
> have considered it for pgoutput plugin which doesn't have explicit
> skip-empty-xacts option. I think the optimization would be useful in
> setups where multiple publications and long transactions are common.
> Any reason not to have it.
>

I don't remember any reason why we can't have the same optimization
for streamed transactions. IIRC, we implemented this optimization
because we got reports for extra messages for short empty-transactions
but if you see any practical cases where it could be useful for
streamed transactions as well then feel free to propose a patch.

--
With Regards,
Amit Kapila.