Re: Report checkpoint progress with pg_stat_progress_checkpoint (was: Report checkpoint progress in server logs)

On Tue, 15 Feb 2022 at 13:16, Nitin Jadhav
<nitinjadhavpostgres(at)gmail(dot)com> wrote:
>
> > Apart from above fields, I am planning to add few more fields to the
> > view in the next patch. That is, process ID of the backend process
> > which triggered a CHECKPOINT command, checkpoint start location, filed
> > to indicate whether it is a checkpoint or restartpoint and elapsed
> > time of the checkpoint operation. Please share your thoughts. I would
> > be happy to add any other information that contributes to showing the
> > progress of checkpoint.
>
> The progress reporting mechanism of postgres uses the
> 'st_progress_param' array of 'PgBackendStatus' structure to hold the
> information related to the progress. There is a function
> 'pgstat_progress_update_param()' which takes 'index' and 'val' as
> arguments and updates the 'val' to corresponding 'index' in the
> 'st_progress_param' array. This mechanism works fine when all the
> progress information is of type integer as the data type of
> 'st_progress_param' is of type integer. If the progress data is of
> different type than integer, then there is no easy way to do so.

Progress parameters are int64, so all of the new 'checkpoint start
location' (lsn = uint64), 'triggering backend PID' (int), 'elapsed
time' (store as start time in stat_progress, timestamp fits in 64
bits) and 'checkpoint or restartpoint?' (boolean) would each fit in a
current stat_progress parameter. Some processing would be required at
the view, but that's not impossible to overcome.

Kind regards,

Matthias van de Meent