Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and more?)

On Mon, Apr 3, 2023 at 12:13 AM Pavel Luzanov <p(dot)luzanov(at)postgrespro(dot)ru> wrote:
>
> Hello,
>
> I found that the 'standalone backend' backend type is not documented
> right now.
> Adding something like (from commit message) would be helpful:
>
> Both the bootstrap backend and single user mode backends will have
> backend_type STANDALONE_BACKEND.

Thanks for the report.

Attached is a tiny patch to add standalone backend type to
pg_stat_activity documentation (referenced by pg_stat_io).

I mentioned both the bootstrap process and single user mode process in
the docs, though I can't imagine that the bootstrap process is relevant
for pg_stat_activity.

I also noticed that the pg_stat_activity docs call background workers
"parallel workers" (though it also mentions that extensions could have
other background workers registered), but this seems a bit weird because
pg_stat_activity uses GetBackendTypeDesc() and this prints "background
worker" for type B_BG_WORKER. Background workers doing parallelism tasks
is what users will most often see in pg_stat_activity, but I feel like
it is confusing to have it documented as something different than what
would appear in the view. Unless I am misunderstanding something...

- Melanie