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

On Wed, Sep 29, 2021 at 4:46 PM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
>
> On Mon, Sep 27, 2021 at 2:58 PM Melanie Plageman
> <melanieplageman(at)gmail(dot)com> wrote:
> >
> > On Fri, Sep 24, 2021 at 5:58 PM Melanie Plageman
> > <melanieplageman(at)gmail(dot)com> wrote:
> > >
> > > On Thu, Sep 23, 2021 at 5:05 PM Melanie Plageman
> > > <melanieplageman(at)gmail(dot)com> wrote:
> > > The only remaining TODOs are described in the commit message.
> > > most critical one is that the reset message doesn't work.
> >
> > v10 is attached with updated comments and some limited code refactoring
>
> v11 has fixed the oversize message issue by sending a reset message for
> each backend type. Now, we will call GetCurrentTimestamp
> BACKEND_NUM_TYPES times, so maybe I should add some kind of flag to the
> reset message that indicates the first message so that all the "do once"
> things can be done at that point.
>
> I've also fixed a few style/cosmetic issues and updated the commit
> message with a link to the thread [1] where I proposed smgrwrite() and
> smgrextend() wrappers (which is where I propose to call
> pgstat_incremement_buffer_access_type() for unbuffered writes and
> extends).
>
> - Melanie
>
> [1] https://www.postgresql.org/message-id/CAAKRu_aw72w70X1P%3Dba20K8iGUvSkyz7Yk03wPPh3f9WgmcJ3g%40mail.gmail.com

v12 (attached) has various style and code clarity updates (it is
pgindented as well). I also added a new commit which creates a utility
function to make a tuplestore for views that need one in pgstatfuncs.c.

Having received some offlist feedback about the names BufferAccessType
and BufferType being confusing, I am planning to rename these variables
and all of the associated functions. I agree that BufferType and
BufferAccessType are confusing for the following reasons:
- They sound similar.
- They aren't very precise.
- One of the types of buffers is not using a Postgres buffer.

So far, the proposed alternative is IO_Op or IOOp for BufferAccessType
and IOPath for BufferType.

- Melanie