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

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Accounting of zero-filled buffers in EXPLAIN (BUFFERS)
Date: 2018-11-23 07:39:13
Message-ID: CAEepm=3AWXmXg4ZM5iO3_=ZcGw7z-s=JeVpLKnk1svdqzA+bKw@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Mon, Nov 19, 2018 at 5:24 PM Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> At Sat, 17 Nov 2018 11:15:54 -0300, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote in <20181117141554(dot)4dkx2u4j6md3bqdh(at)alvherre(dot)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.

--
Thomas Munro
http://www.enterprisedb.com

Attachment Content-Type Size
0001-Don-t-count-zero-filled-buffers-as-read-in-EXPLAI-v2.patch application/octet-stream 1.8 KB

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Thomas Munro 2018-11-23 07:54:42 pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.
Previous Message John Naylor 2018-11-23 06:26:43 Re: WIP: Avoid creation of the free space map for small tables