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

On 05.04.2023 03:41, Melanie Plageman wrote:
> On Tue, Apr 4, 2023 at 4:35 PM Pavel Luzanov <p(dot)luzanov(at)postgrespro(dot)ru> wrote:
>
>> After a little thought... I'm not sure about the term 'bootstrap
>> process'. I can't find this term in the documentation.
> There are various mentions of "bootstrap" peppered throughout the docs
> but no concise summary of what it is. For example, initdb docs mention
> the "bootstrap backend" [1].
>
> Interestingly, 910cab820d0 added "Bootstrap superuser" in November. This
> doesn't really cover what bootstrapping is itself, but I wonder if that
> is useful? If so, you could propose a glossary entry for it?
> (preferably in a new thread)

I'm not sure if this is the reason for adding a new entry in the glossary.

>> Do I understand correctly that this is a postmaster? If so, then the
>> postmaster process is not shown in pg_stat_activity.
> No, bootstrap process is for initializing the template database. You
> will not be able to see pg_stat_activity when it is running.

Oh, it's clear to me now. Thank you for the explanation.

> You can query pg_stat_activity from single user mode, so it is relevant
> to pg_stat_activity also. I take your point that bootstrap mode isn't
> relevant for pg_stat_activity, but I am hesitant to add that distinction
> to the pg_stat_io docs since the reason you won't see it in
> pg_stat_activity is because it is ephemeral and before a user can access
> the database and not because stats are not tracked for it.
>
> Can you think of a way to convey this?

See my attempt attached.
I'm not sure about the wording. But I think we can avoid the term
'bootstrap process'
by replacing it with "database cluster initialization", which should be
clear to everyone.

--
Pavel Luzanov
Postgres Professional: https://postgrespro.com