Re: NOTIFY command impact

From: François Beaulieu <Francois(dot)Beaulieu(at)sbktelecom(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Rob Brucks <rob(dot)brucks(at)rackspace(dot)com>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: NOTIFY command impact
Date: 2017-02-22 00:05:06
Message-ID: 9880ADDE-8F2F-4F90-85B1-7270A3D94A50@sbktelecom.com
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> On Feb 21, 2017, at 6:03 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Rob Brucks <rob(dot)brucks(at)rackspace(dot)com> writes:
>> If a notify is sent and then PG is immediately shut down, wouldn't PG want to save that message for processing after startup?
>> Or is the message just discarded?
>
> NOTIFY data is not saved across a shutdown or crash.
>
> (The reason it goes into the WAL stream is so that you can have listeners
> on replication slaves, not for recovery purposes.)
>
> regards, tom lane
>

Are we sure that replication slaves can have listeners? When I tried it on 9.4.10, I got the following message:

"ERROR: cannot execute LISTEN during recovery"

-=Frank

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