Subject: Re: [HACKERS] WAL logging problem in 9.4.3?
To: Robert Haas <robertmhaas@gmail.com>,
 Kyotaro Horiguchi <horikyota.ntt@gmail.com>
References: <20190828.154210.204505676.horikyota.ntt@gmail.com>
 <20191025.131251.322449872063947371.horikyota.ntt@gmail.com>
 <CAKPRHzJSgMuNeCtKgSxBJd2zOgK3BKL13Pkn_6_Sr9qXCRU=fQ@mail.gmail.com>
 <CA+TgmoYzTPpxvPUUs_ALW1YYNxV6mCrj6zwqnaN6FqdNc1JUzw@mail.gmail.com>
Cc: Noah Misch <noah@leadboat.com>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>,
 Dmitry Dolgov <9erthalion6@gmail.com>,
 Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, hlinnaka <hlinnaka@iki.fi>,
 Michael Paquier <michael@paquier.xyz>
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
Message-ID: <1f9a76fe-6f77-eb5f-9292-9b1c92f4f5bd@2ndquadrant.com>
Date: Fri, 22 Nov 2019 13:21:31 +0100
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On 2019-11-05 22:16, Robert Haas wrote:
> First, I'd like to restate my understanding of the problem just to see
> whether I've got the right idea and whether we're all on the same
> page. When wal_level=minimal, we sometimes try to skip WAL logging on
> newly-created relations in favor of fsync-ing the relation at commit
> time.

How useful is this behavior, relative to all the effort required?

Even if the benefit is significant, how many users can accept running 
with wal_level=minimal and thus without replication or efficient backups?

Is there perhaps an alternative approach involving unlogged tables to 
get a similar performance benefit?

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services