Re: Freeze avoidance of very large table.

From: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(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>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Subject: Re: Freeze avoidance of very large table.
Date: 2015-10-05 10:31:18
Message-ID: CAD21AoDDY6QGxz49qv072oWw6RsMLyd67Db7Rf-FNHSeRcd65Q@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Sat, Oct 3, 2015 at 3:41 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Oct 2, 2015 at 11:23 AM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:
>>> + /* all-frozen information is also cleared at the same time */
>>> PageClearAllVisible(page);
>>> + PageClearAllFrozen(page);
>>
>> I wonder if it makes sense to have a macro to clear both in unison,
>> which seems a very common pattern.
>
> I think PageClearAllVisible should clear both, and there should be no
> other macro. There is no event that causes a page to cease being
> all-visible that does not also cause it to cease being all-frozen.
> You might think that deleting or locking a tuple would fall into that
> category - but nope, XMAX needs to be cleared or the tuple pruned, or
> there will be problems after wraparound.
>

Thank you for your advice.
I understood.

I changed the patch so that PageClearAllVisible clear both bits, and
removed ClearAllFrozen.
Attached the latest v16 patch which contains draft version documentation patch.

Regards,

--
Masahiko Sawada

Attachment Content-Type Size
000_add_frozen_bit_into_visibilitymap_v16.patch text/x-patch 74.3 KB

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Magnus Hagander 2015-10-05 10:32:17 Re: No Issue Tracker - Say it Ain't So!]
Previous Message Kyotaro HORIGUCHI 2015-10-05 10:07:38 Re: Connection string parameter 'replication' in documentation