From: Bruce Momjian <bruce@momjian.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: shangzi.x@columbia.edu, Pg Docs <pgsql-docs@lists.postgresql.org>
Subject: Re: relpages in pg_class
Date: Fri, 19 Aug 2022 15:16:32 -0400
Message-ID: <Yv/hkEf1fFDIGl6m@momjian.us> (raw)
In-Reply-To: <CAH2-Wz=xFBK69PiXo8aFQhDYvKqVtaVTQfS+LD1aAtacbPfh=w@mail.gmail.com>
References: <20220819160133.l2m47puqpjzk3mrh@alvherre.pgsql>
<3203690.1660927195@sss.pgh.pa.us>
<CAH2-Wz=xFBK69PiXo8aFQhDYvKqVtaVTQfS+LD1aAtacbPfh=w@mail.gmail.com>
On Fri, Aug 19, 2022 at 11:25:52AM -0700, Peter Geoghegan wrote:
> On Fri, Aug 19, 2022 at 9:40 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Yeah, we use "blocks" and "pages" interchangeably, which is something
> > I don't feel a need to change; but evidently the OP didn't realize that.
> > This is a job for the glossary, perhaps?
>
> I think that they're synonyms that can often (but not always) be used
> interchangeably. I *think* that this understanding is shared by other
> people, though I should check. Here goes:
>
> To me, "block" emphasizes on-disk/relfilenode storage. Something that
> exists at a particular physical offset in a particular file (a
> BlockNumber + relfilenode). On the other hand, the term "page"
> emphasizes the in-memory format, and the indirection provided by the
> bufpage.c slotted page format (i.e. line pointer array indirection).
Yes, I have heard the block-disk, page-memory explanation before.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com
Indecision is a decision. Inaction is an action. Mark Batterson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-docs@postgresql.org
Cc: bruce@momjian.us, pg@bowt.ie, tgl@sss.pgh.pa.us, alvherre@alvh.no-ip.org, pgsql-docs@lists.postgresql.org
Subject: Re: relpages in pg_class
In-Reply-To: <Yv/hkEf1fFDIGl6m@momjian.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox