Re: bgwriter doesn't flush WAL stats

Hi,

Created a commitfest entry for this.
Link: https://commitfest.postgresql.org/43/4405/

Regards,
Nazir Bilal Yavuz
Microsoft

On Thu, 22 Jun 2023 at 17:03, Melanie Plageman <melanieplageman(at)gmail(dot)com>
wrote:

> On Wed, Jun 21, 2023 at 9:49 PM Kyotaro Horiguchi
> <horikyota(dot)ntt(at)gmail(dot)com> wrote:
> > Regarding the second patch, it introduces WAL IO time as a
> > IOCONTEXT_NORMAL/IOOBJECT_WAL, but it doesn't seem to follow the
> > convention or design of the pgstat_io component, which primarily
> > focuses on shared buffer IOs.
>
> I haven't reviewed the patch yet, but in my opinion having an
> IOOBJECT_WAL makes sense. I imagined that we would add WAL as an
> IOObject along with others such as an IOOBJECT_BYPASS for "bypass" IO
> (IO done through the smgr API directly) and an IOOBJECT_SPILL or
> something like it for spill files from joins/aggregates/etc.
>
> > > I do have a question about this.
> > > So, if we were to start tracking WAL IO would it fit within this
> > > paradigm to have a new IOPATH_WAL for WAL or would it add a separate
> > > dimension?
>
> Personally, I think WAL fits well as an IOObject. Then we can add
> IOCONTEXT_INIT and use that for WAL file initialization and
> IOCONTEXT_NORMAL for normal WAL writes/fysncs/etc. I don't think we
> need a new dimension for it as it feels like an IO target just like
> shared buffers and temporary buffers do. I think we should save adding
> new dimensions for relationships that we can't express in the existing
> paradigm.
>
> - Melanie
>