Re: Accounting of zero-filled buffers in EXPLAIN (BUFFERS)

Haribabu Kommi <kommi.haribabu@gmail.com>

From: Haribabu Kommi <kommi.haribabu@gmail.com>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Alvaro Herrera <alvherre@2ndquadrant.com>, David Rowley <david.rowley@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-11-27T01:53:05Z
Lists: pgsql-hackers
On Fri, Nov 23, 2018 at 6:39 PM Thomas Munro <thomas.munro@enterprisedb.com>
wrote:

> On Mon, Nov 19, 2018 at 5:24 PM Kyotaro HORIGUCHI
> <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> > At Sat, 17 Nov 2018 11:15:54 -0300, Alvaro Herrera <
> alvherre@2ndquadrant.com> wrote in
> <20181117141554.4dkx2u4j6md3bqdh@alvherre.pgsql>
> > > Is this patch committable now?
> >
> > I don't think so. We should make a decision on a point.
> >
> > I was a bit confused (sorry) but IIUIC Haribabu suggested that
> > the RBM_ZERO_ON_ERROR case should be included to read (not just
> > ignored). I'm on it.  I think that RPM_ZERO_* other than ON_ERROR
> > cases could be a kind of hit but I don't insist on it.
> >
> > So, I think we should decide on at least the ON_ERROR case before
> > this becomes commttable.
>
> Agreed, RBM_ZERO_ON_ERROR needs to be counted as a read.  Here's a new
> version like that.
>
> > The another counter could be another issue. I don't object to add
> > the counter but I'm not sure what is the suitable name.
>
> I think that might be interesting information in the future, but let's
> consider that for a later patch.
>

Thanks for the updated patch. It looks good.
I marked it in the commitfest as ready for committer.

Regards,
Haribabu Kommi
Fujitsu Australia

Commits

  1. Don't count zero-filled buffers as 'read' in EXPLAIN.