Re: Report bytes and transactions actually sent downtream

Hi,

On Tue, Sep 23, 2025 at 04:15:14PM +0530, Ashutosh Bapat wrote:
> On Tue, Sep 23, 2025 at 12:14 PM Bertrand Drouvot
> <bertranddrouvot.pg@gmail.com> wrote:
> >
> > - create a table and use pg_logical_slot_get_changes with ('skip-empty-xacts', '1')
> > then I don't see plugin_sent_bytes increasing (which makes sense) but I also don't
> > see plugin_filtered_bytes increasing. I think that would make sense to also increase
> > plugin_filtered_bytes in this case (and for the other options that would skip
> > sending data). Thoughts?
> 
> Thanks for bringing this up. I don't think we discussed this
> explicitly in the thread. The changes which are filtered out by the
> core itself e.g. changes to the catalogs or changes to other databases
> or changes from undesired origins are not added to the reorder buffer.
> They are not counted in total_bytes. The transactions containing only
> such changes are not added to reorder buffer, so even total_txns does
> not count such empty transactions. If we count these changes and
> transactions in plugin_filtered_bytes, and plugin_filtered_txns, that
> would create an anomaly - filtered counts being higher than total
> counts. Further since core does not add these changes and transactions
> to the reorder buffer, there is no way for a plugin to know about
> their existence and hence count them. Does that make sense?

Yes. Do you think that the doc in the patch is clear enough regarding this point?
I mean the doc looks correct (mentioning the output plugin) but would that make
sense to insist that core filtering is not taken into account?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
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