From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: yigongh@gmail.com
Cc: pgsql-docs@lists.postgresql.org
Subject: Re: The suggestion of reducing autovacuum_vacuum_cost_delay should be documented
Date: Tue, 12 May 2020 19:30:56 -0400
Message-ID: <20200512233056.GF4666@momjian.us> (raw)
In-Reply-To: <23940.1589325967@sss.pgh.pa.us>
References: <158927918783.656.11973436145559215458@wrigleys.postgresql.org>
<20200512214014.GD4666@momjian.us>
<20200512214101.GA21408@momjian.us>
<CAKFQuwY+RMFFM1Y44=2dpi_8TyTq_4yrLUG6VjWnzgQAhG6o7Q@mail.gmail.com>
<20200512224520.GE4666@momjian.us>
<23940.1589325967@sss.pgh.pa.us>
On Tue, May 12, 2020 at 07:26:07PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > On Tue, May 12, 2020 at 03:38:16PM -0700, David G. Johnston wrote:
> >> The proposal is to document in versions 9.4 to 11 that the recommended value
> >> for the setting is 2ms while for reasons of continuity the default in these
> >> versions is 20ms.
> >> I don't really see any harm in it. Its not like the choice to reduce the value
> >> was made because of new features introduced in 12 - it was a re-evaluation of a
> >> 15 year old default.
>
> > Well, we really need to have some general discussion about whether
> > changing defaults in major releases should trigger a mention to change
> > the defaults in back branches. This is something that would have to be
> > discussed on the hackers list.
>
> It's not immediately obvious that the new default value established in
> version N is appropriate for version N-minus-several. Certainly, whatever
> testing was done to justify the new default wouldn't have been done on old
> versions; and there might have been relevant changes.
>
> In short: nope, I'm not on board with blindly back-patching such
> recommendations.
That was my analysis too.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EnterpriseDB https://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
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-docs@postgresql.org
Cc: bruce@momjian.us, tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, yigongh@gmail.com, pgsql-docs@lists.postgresql.org
Subject: Re: The suggestion of reducing autovacuum_vacuum_cost_delay should be documented
In-Reply-To: <20200512233056.GF4666@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