Date: Sat, 2 Oct 2021 10:41:54 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
	David Steele <david@pgmasters.net>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	Bruce Momjian <bruce@momjian.us>, Paul Guo <guopa@vmware.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Brown <michael.brown@discourse.org>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: should frontend tools use syncfs() ?
Message-ID: <20211002154154.GD27491@telsasoft.com>
References: <20210930004340.GM831@telsasoft.com>
 <YVUz0Ay9KshniWBe@paquier.xyz>
 <CA+hUKGJYChC0witfaTrURsds4Y6cOnCb1-P2UvBvui8pwQhTEA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: 
 <CA+hUKGJYChC0witfaTrURsds4Y6cOnCb1-P2UvBvui8pwQhTEA@mail.gmail.com>
User-Agent: Mutt/1.9.4 (2018-02-28)
Archived-At: 
 <https://www.postgresql.org/message-id/20211002154154.GD27491%40telsasoft.com>
Precedence: bulk

On Thu, Sep 30, 2021 at 05:08:24PM +1300, Thomas Munro wrote:
> On Thu, Sep 30, 2021 at 4:49 PM Michael Paquier <michael@paquier.xyz> wrote:
> > fsync_pgdata() is going to manipulate many inodes anyway, because
> > that's a code path designed to do so.  If we know that syncfs() is
> > just going to be better, I'd rather just call it by default if
> > available and not add new switches to all the frontend tools in need
> > of flushing the data folder, switches that are not documented in your
> > patch.
> 
> If we want this it should be an option, because it flushes out data
> other than the pgdata dir, and it doesn't report errors on old
> kernels.

I ran into bad performance of initdb --sync-only shortly after adding it to my
db migration script, so added initdb --syncfs.

I found that with sufficiently recent coreutils, I can do what's wanted by calling 
/bin/sync -f /datadir

Since it's not integrated into initdb, it's necessary to include each
tablespace and wal.

-- 
Justin