Re: Some problems about cascading replication

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Some problems about cascading replication
Date: 2011-08-17 04:27:11
Message-ID: CAHGQGwH29TPJ9Aq=r5Pm1MCjvwV8H3Q6DEs7+=YxqNo+RYzUTw@mail.gmail.com
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On Tue, Aug 16, 2011 at 11:56 PM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> I think there's a race condition here. If a walsender is just starting up,
> it might not have registered itself as a walsender yet. It's actually been
> there before this patch to suppress the log message.

Right. To address this problem, I changed the patch so that "dead-end"
walsender (i.e., cascading walsender even though recovery is not in
progress) always emits the log message. This change would cause
duplicate log messages if the standby promotion is requested while
multiple walsenders including "dead-end" one are running. But since
this is less likely to happen, I don't think it's worth writing code to
suppress those duplicate log messages. Comments?

I attached the updated version of the patch.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

Attachment Content-Type Size
fix_some_problems_about_cascading_replication_v2.patch text/x-patch 2.7 KB

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