Re: Add index scan progress to pg_stat_progress_vacuum

On Thu, Apr 06, 2023 at 03:14:20PM +0000, Imseih (AWS), Sami wrote:
>> Could it be worth thinking about a different design where
>> the value incremented and the parameters of
>> pgstat_progress_update_param() are passed through the 'P' message
>> instead?
> 
> I am not sure how this is different than the approach suggested.
> In the current design, the 'P' message is used to pass the
> ParallelvacuumState to parallel_vacuum_update_progress which then
> calls pgstat_progress_update_param.

The arguments of pgstat_progress_update_param() would be given by the
worker directly as components of the 'P' message.  It seems to me that
this approach would have the simplicity to not require the setup of a
shmem area for the extra counters, and there would be no need for a
callback.  Hence, the only thing the code paths of workers would need
to do is to call this routine, then the leaders would increment their
progress when they see a CFI to process the 'P' message.  Also, I
guess that we would only need an interface in backend_progress.c to
increment counters, like pgstat_progress_incr_param(), but usable by
workers.  Like a pgstat_progress_worker_incr_param()?
--
Michael