Re: Taking into account syncrep position in flush_lsn reported by apply worker

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Arseny Sher <ars(at)neon(dot)tech>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Taking into account syncrep position in flush_lsn reported by apply worker
Date: 2024-08-13 03:35:48
Message-ID: CAA4eK1L9WetnoZJe5n+w4A6499hZUEFqTF9QPYPkeSSX5205+Q@mail.gmail.com
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On Mon, Aug 12, 2024 at 3:43 PM Arseny Sher <ars(at)neon(dot)tech> wrote:
>
> Sorry for the poor formatting of the message above, this should be better:
>
> Hey. Currently synchronous_commit is disabled for logical apply worker
> on the ground that reported flush_lsn includes only locally flushed data
> so slot (publisher) preserves everything higher than this, and so in
> case of subscriber restart no data is lost. However, imagine that
> subscriber is made highly available by standby to which synchronous
> replication is enabled. Then reported flush_lsn is ignorant of this
> synchronous replication progress, and in case of failover data loss may
> occur if subscriber managed to ack flush_lsn ahead of syncrep.
>

Won't the same can be achieved by enabling the synchronous_commit
parameter for a subscription?

--
With Regards,
Amit Kapila.

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