From: Bruce Momjian <bruce@momjian.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Kevin Grittner <kgrittn@mail.com>
Cc: Amit Kapila <amit.kapila@huawei.com>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: 9.2.1 & index-only scans : abnormal heap fetches after VACUUM FULL
Date: Thu, 28 Nov 2013 17:38:05 -0500
Message-ID: <20131128223805.GC20216@momjian.us> (raw)
In-Reply-To: <CA+TgmoYBnQfS4ACVmAq9i4KQ+EOJo053oHhsfBkWEnLNCbsu5Q@mail.gmail.com>
References: <20130112191404.255800@gmx.com>
<20131127213320.GA3785@momjian.us>
<CA+TgmoYBnQfS4ACVmAq9i4KQ+EOJo053oHhsfBkWEnLNCbsu5Q@mail.gmail.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-hackers>
On Thu, Nov 28, 2013 at 05:17:07PM -0500, Robert Haas wrote:
> > I need to know this is the right approach, and need to know what things
> > are wrong or missing.
>
> The fact that you've needed to modify SetHintBits() to make this work
> is pretty nasty. I'm not exactly sure what to do about that, but it
> doesn't seem good.
Hey, if that's the worst of the problems, I will be very happy. There
is a sense that because we are not using the shared buffer cache and not
WAL logging, we have to skip some stuff.
> This patch also has the desirable but surprising consequence that hint
> bits will be set as a side effect of update_page_vm(), which means
> that you'd better do that BEFORE checksumming the page.
Yes, I already saw that and fixed it in my git tree.
> I wonder if we ought to mark each page as all-visible in
> raw_heap_insert() when we first initialize it, and then clear the flag
> when we come across a tuple that isn't all-visible. We could try to
> set hint bits on the tuple before placing it on the page, too, though
> I'm not sure of the details.
I went with the per-page approach because I wanted to re-use the vacuum
lazy function. Is there some other code that does this already? I am
trying to avoid yet-another set of routines that would need to be
maintained or could be buggy. This hit bit setting is tricky.
And thanks much for the review!
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
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-hackers@postgresql.org
Cc: bruce@momjian.us, robertmhaas@gmail.com, kgrittn@mail.com, amit.kapila@huawei.com, josh@agliodbs.com
Subject: Re: 9.2.1 & index-only scans : abnormal heap fetches after VACUUM FULL
In-Reply-To: <20131128223805.GC20216@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