Re: Freeze avoidance of very large table.

From: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, Robert Haas <robertmhaas(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>, 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 16:23:08
Message-ID: CAD21AoC=67JRLd5BAct=dx7MGHNKR3H7R0G-gnzax0xZAx3M6Q@mail.gmail.com
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On Mon, Oct 5, 2015 at 11:03 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Fri, Oct 2, 2015 at 8:14 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>> +#define Anum_pg_class_relallfrozen 12
>>> Why is pg_class.relallfrozen necessary? ISTM that there is no user of it now.
>>
>> The relallfrozen would be useful for user to estimate time to vacuum
>> freeze or anti-wrapping vacuum before being done them actually.
>> (Also this value is used on regression test.)
>> But this information is not used on planning like relallvisible, so it
>> would be good to move this information to another system view like
>> pg_stat_*_tables.
>
> Or make pgstattuple and pgstattuple_approx report even the number
> of frozen tuples?
>

But we cannot know the number of frozen pages without installation of
pageinspect module.
I'm a bit concerned about that the all projects cannot install
extentension module into postgresql on production environment.
I think we need to provide such feature at least into core.
Thought?

Regards,

--
Masahiko Sawada

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