Date: Tue, 16 Sep 2025 21:45:39 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Nazneen Jafri <jafrinazneen@gmail.com>, pgsql-bugs@lists.postgresql.org
Subject: Re: Read Replica termination occurs when its
 max_active_replication_origins setting is lower than the primary
Message-ID: <aMog06qbmvLLcFSw@nathan>
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On Tue, Sep 16, 2025 at 04:42:39PM -0700, Masahiko Sawada wrote:
> On Tue, Sep 16, 2025 at 3:52 PM Nazneen Jafri <jafrinazneen@gmail.com> wrote:
>> The parameter max_active_replication_origins should be added to the list
>> of mandatory settings that must match between primary and replica during
>> creation
>>
>> [...]
> 
> Thank you for the report!
> 
> As reported, the standby could not continue the recovery (especially
> replaying XLOG_REPLORIGIN_ records) if its
> max_active_replication_origins is less than the primary's setting. One
> idea to fix this issue is to require for standbys to have at least the
> same  max_active_replication_origins value as the primary as we do for
> other GUC parameters such as max_worker_processes and max_wal_senders.
> It needs to add max_active_replication_origins to the control file and
> bumps the PG_CONTROL_VERSION. Given that we've released 18RC1 and
> probably are close to 18 release, I'd like to hear opinions whether
> such a fix is acceptable or not.

I haven't tried reproducing it on older versions (with
max_replication_slots instead of max_active_replication_origins), but after
looking at the code for a bit, I'm growing skeptical that this is new to
v18.  In any case, the PANIC provides a clear error message, which is
roughly the same as what we'd say with the control file approach, right?

-- 
nathan