Re: Add index scan progress to pg_stat_progress_vacuum

Thanks for the feedback. I agree with the feedback, except
for 

>    need to have ParallelVacuumProgress. I see
>    parallel_vacuum_update_progress() uses this value but I think it's
>    better to pass ParallelVacuumState to via IndexVacuumInfo.

I was trying to avoid passing a pointer to
ParallelVacuumState in IndexVacuuminfo.

ParallelVacuumProgress is implemented in the same
way as VacuumSharedCostBalance and 
VacuumActiveNWorkers. See vacuum.h

These values are reset at the start of a parallel vacuum cycle
and reset at the end of an index vacuum cycle.

This seems like a better approach and less invasive.
What would be a reason not to go with this approach?


> parallel_vacuum_update_progress() is typically called every 1GB so I
> think we don't need to worry about unnecessary update. Also, I think
> this code doesn't work when pgstat_track_activities is false. Instead,
> I think that in parallel_wait_for_workers_to_finish(), we can check
> the value of pvs->nindexes_completed and update the progress if there
> is an update or it's first time.

I agree that we don’t need to worry about unnecessary updates
in parallel_vacuum_update_progress since we are calling
every 1GB. I also don't think we should do anything additional
in parallel_wait_for_workers_to_finish since here we are only
updating every 1 second.

Thanks,

Sami Imseih
Amazon Web Services