Re: Freeze avoidance of very large table.

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, 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>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Freeze avoidance of very large table.
Date: 2015-11-30 18:16:02
Message-ID: 20151130181602.GB19371@momjian.us
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On Mon, Nov 30, 2015 at 07:05:21PM +0100, Andres Freund wrote:
> On 2015-11-30 12:58:43 -0500, Bruce Momjian wrote:
> > I would not bother mentioning this detail in the pg_upgrade manual page:
> >
> > + Since the format of visibility map has been changed in version 9.6,
> > + <application>pg_upgrade</> creates and rewrite new <literal>'_vm'</literal>
> > + file even if upgrading from 9.5 or before to 9.6 or later with link mode (-k).
>
> Might be worthwhile to keep as that influences the runtime for link mode
> when migrating <9.6 -> 9.6.

It is hard to see that it would have a measurable duration. The
pg_upgrade docs are already very long and this detail doesn't seems
significant. Can someone test the overhead?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Roman grave inscription +

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