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Subject: Re: Reliable WAL file shipping over unreliable network
From: scott ribe <scott_ribe@elevated-dev.com>
In-Reply-To: <debd4205-e27a-cd9d-9169-6748e65083a2@shopzeus.com>
Date: Wed, 28 Feb 2018 09:38:57 -0700
Cc: pgsql-admin@lists.postgresql.org
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Message-Id: <BA4A1866-95B0-49C6-8CD1-3D1B60A7837E@elevated-dev.com>
References: <dd116172-3ddf-ee56-57f3-6e18d49abf8e@shopzeus.com>
 <400AC9CD-1E43-422C-A689-70BDBAFF231E@elevated-dev.com>
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 <debd4205-e27a-cd9d-9169-6748e65083a2@shopzeus.com>
To: =?utf-8?Q?Nagy_L=C3=A1szl=C3=B3_Zsolt?= <gandalf@shopzeus.com>
Precedence: bulk

On Feb 28, 2018, at 8:46 AM, Nagy L=C3=A1szl=C3=B3 Zsolt =
<gandalf@shopzeus.com> wrote:
>=20
> Another problem with rsync might be that it does not know if a WAL =
file
> on the source side is growing (e.g. being written) and it might start
> copy that before it is fully flushed to disk. I see this as a big
> problem, but I don't have experience.

You use rsync in the archive command, not by itself. Postgres does not =
try to copy the file until it is ready.

> E.g. move the file into the archive dir only after it has been fully
> copied to the destination volume. But then we still have the problem =
of
> partially written files on the slave side.

No, you do not have that problem at all.

Given an unreliable network, you probably do want to use --partial


--
Scott Ribe
https://www.linkedin.com/in/scottribe/
(303) 722-0567