Re: adding status for COPY progress report

On Tue, May 24, 2022 at 12:37 PM Matthias van de Meent <
boekewurm+postgres(at)gmail(dot)com> wrote:

> On Tue, 24 May 2022 at 19:13, Zhihong Yu <zyu(at)yugabyte(dot)com> wrote:
> >
> > Hi,
> > Please see attached for enhancement to COPY command progress.
> >
> > The added status column would allow users to get the status of the most
> recent COPY command.
>
> I fail to see the merit of retaining completed progress reporting
> commands in their views after completion, other than making the
> behaviour of the pg_stat_progress-views much more complicated and
> adding overhead in places where we want the system to have as little
> overhead as possible.
>
> Trying to get the status of a COPY command after it finished on a
> different connection seems weird, as that other connection is likely
> to have already disconnected / started another task. To be certain
> that a backend can see the return status of the COPY command, you'd
> have to be certain that the connection doesn't run any other
> _progress-able commands in the following seconds / minutes, which
> implies control over the connection, which means you already have
> access to the resulting status of your COPY command.
>
> Regarding the patch: I really do not like that this leaks entries into
> all _progress views: I get garbage data from e.g. the _create_index
> and _copy views when VACUUM is running, etc, because you removed the
> filter on cmdtype.
> Also, the added fields in CopyToStateData / CopyFromStateData seem
> useless when a pgstat_progress_update_param in the right place should
> suffice.
>
> Kind regards,
>
> Matthias van de Meent
>
Hi,
For #2 above, can you let me know where the pgstat_progress_update_param()
call(s) should be added ?

In my patch, pgstat_progress_update_param() is called from error callback
and EndCopy().

For #1, if I use param18 (which is not used by other views), would that be
better ?

Thanks