Date: Sun, 18 Dec 2022 15:55:00 -0800
From: Nathan Bossart <nathandbossart@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, postgresql@taljaren.se,
	pgsql-bugs@lists.postgresql.org,
	Michael Paquier <michael@paquier.xyz>
Subject: Re: BUG #17717: Regression in vacuumdb (15 is slower than 10/11 and
 possible memory issue)
Message-ID: <20221218235500.GC1476904@nathanxps13>
References: <17717-6c50eb1c7d23a886@postgresql.org>
 <3439037.1671130590@sss.pgh.pa.us>
 <CAH2-Wzne4Wgaaruq-VSY2qWNhxcPRqWUbdwVQPkM81TpaHY_kQ@mail.gmail.com>
 <3544447.1671141436@sss.pgh.pa.us>
 <CAH2-WzkXmYt-K+pQqMqjFgwU7jiykD3amngd5-jkqQF=gST7Og@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: 
 <CAH2-WzkXmYt-K+pQqMqjFgwU7jiykD3amngd5-jkqQF=gST7Og@mail.gmail.com>
Archived-At: 
 <https://www.postgresql.org/message-id/20221218235500.GC1476904%40nathanxps13>
Precedence: bulk

On Thu, Dec 15, 2022 at 08:39:54PM -0800, Peter Geoghegan wrote:
> On Thu, Dec 15, 2022 at 1:57 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I could get behind manual VACUUM not invoking vac_update_datfrozenxid
>> by default, perhaps.  But if it can never call it, then that is a
>> fairly important bit of housekeeping that is unreachable except by
>> autovacuum.  No doubt the people who turn off autovacuum are benighted,
>> but they're still out there.
> 
> I wouldn't mind adding another option for this to VACUUM. We already
> have a couple of VACUUM options that are only really needed as escape
> hatches, or perhaps as testing tools used by individual Postgres
> hackers. Another one doesn't seem too bad. The VACUUM command should
> eventually become totally niche, so I'm not too concerned about going
> overboard here.

Perhaps there could also be an update-datfrozenxid function that vacuumdb
calls when finished with a database.  Even if vacuum becomes smarter about
calling vac_update_datfrozenxid, this might still be worth doing.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com