Re: Freeze avoidance of very large table.

From: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Freeze avoidance of very large table.
Date: 2015-11-24 23:13:31
Message-ID: CAD21AoA2mcg4gcsvP7m91q3b=9q=hUMUS8m+4vnw+n-34W_HwQ@mail.gmail.com
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On Mon, Nov 23, 2015 at 6:27 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Sun, Nov 22, 2015 at 8:16 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
>> Thank you for taking the time to review this patch!
>> The updated version patch is attached.
>
> I am skeptical about just copying the old page header to be two new
> page headers. I don't know what the implications for this will be on
> pd_lsn. Since pg_upgrade can only run on a cluster that was cleanly
> shutdown, I think that just copying it from the old page to both new
> pages it turns into might be fine. But pd_checksum will certainly be
> wrong, breaking pg_upgrade for cases where checksums are turned on in.
> It needs to be recomputed on both new pages. It looks like there is
> no precedence for doing that in pg_upgrade so this will be breaking
> new ground.
>

Yeah, we need to consider to compute checksum if enabled.
I've changed the patch, and attached.
Please review it.

Regards,

--
Masahiko Sawada

Attachment Content-Type Size
000_add_frozen_bit_into_visibilitymap_v27.patch application/octet-stream 91.2 KB

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