From: Laurenz Albe <laurenz.albe@cybertec.at>
To: jesper.pedersen@redhat.com, PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: pg_receivewal documentation
Date: Tue, 09 Jul 2019 11:16:55 +0200
Message-ID: <2fc1658586de9ccdc742a973edf7831e109b7fdb.camel@cybertec.at> (raw)
In-Reply-To: <1427a2d3-1e51-9335-1931-4f8853d90d5e@redhat.com>
References: <1427a2d3-1e51-9335-1931-4f8853d90d5e@redhat.com>
On Thu, 2019-06-27 at 10:06 -0400, Jesper Pedersen wrote:
> Here is a patch for the pg_receivewal documentation to highlight that
> WAL isn't acknowledged to be applied.
I think it is a good idea to document this, but I have a few quibbles
with the patch as it is:
- I think there shouldn't be commas after the "note" and before the "if".
Disclaimer: I am not a native speaker, so I am lacking authority.
- The assertion is wrong. "on" (remote flush) is perfectly fine
for synchronous_commit, only "remote_apply" is a problem.
- There is already something about "--synchronous" in the "Description"
section. It might make sense to add the additional information there.
How about the attached patch?
Yours,
Laurenz Albe
Attachments:0001-Better-documentation-for-pg_receivewal-synchronous.patch (text/x-patch, 1.2K) download
From c18b4b384a963e04cc5b5b50537c150858824f0a Mon Sep 17 00:00:00 2001
From: Laurenz Albe <laurenz.albe@cybertec.at>
Date: Tue, 9 Jul 2019 11:15:09 +0200
Subject: [PATCH] Better documentation for "pg_receivewal --synchronous"
"synchronous_commit" must not be set to "remote_apply" because
pg_receivewal doesn't apply WAL.
---
doc/src/sgml/ref/pg_receivewal.sgml | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/ref/pg_receivewal.sgml b/doc/src/sgml/ref/pg_receivewal.sgmlindex 0506120c00..4393eeee2c 100644--- a/doc/src/sgml/ref/pg_receivewal.sgml+++ b/doc/src/sgml/ref/pg_receivewal.sgml@@ -52,7 +52,10 @@ PostgreSQL documentation
Unlike the WAL receiver of a PostgreSQL standby server, <application>pg_receivewal</application>
by default flushes WAL data only when a WAL file is closed.
The option <option>--synchronous</option> must be specified to flush WAL data
- in real time.+ in real time. Note that while WAL will be flushed with this setting,+ it will never be applied, so <xref linkend="guc-synchronous-commit"/> must+ not be set to <literal>remote_apply</literal> if <application>pg_receivewal</application>+ is the only synchronous standby.
</para>
<para>
--
2.20.1
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To: pgsql-hackers@postgresql.org
Cc: laurenz.albe@cybertec.at
Subject: Re: pg_receivewal documentation
In-Reply-To: <2fc1658586de9ccdc742a973edf7831e109b7fdb.camel@cybertec.at>
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