Subject: Re: Improve handling of parameter differences in physical replication
To: Masahiko Sawada <masahiko.sawada@2ndquadrant.com>,
 Alvaro Herrera <alvherre@2ndquadrant.com>
References: <4ad69a4c-cc9b-0dfe-0352-8b1b0cd36c7b@2ndquadrant.com>
 <20200228153331.GA31634@alvherre.pgsql>
 <CA+fd4k4ehrboiEB8GFbe-gpiVyFO_cPE57ZpBhPUgJtpCdhC7Q@mail.gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
Message-ID: <ecd7ad33-c4dd-7587-ec0e-87729852bc3e@2ndquadrant.com>
Date: Mon, 9 Mar 2020 10:45:54 +0100
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On 2020-03-09 09:11, Masahiko Sawada wrote:
> I think after recovery is paused users will be better to restart the
> server rather than resume the recovery. I agree with this idea but I'm
> slightly concerned that users might not realize that recovery is
> paused until they look at that line in server log or at
> pg_stat_replication because the standby server is still functional. So
> I think we can periodically send WARNING to inform user that we're
> still waiting for parameter change and restart.

I think that would be annoying, unless you create a system for 
configuring those periodic warnings.

I imagine in a case like having set max_prepared_transactions but never 
actually using prepared transactions, people will just ignore the 
warning until they have their next restart, so it could be months of 
periodic warnings.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services