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Re: BUG: Cascading standby fails to reconnect after falling back to archive recovery

Fujii Masao <masao.fujii@gmail.com>

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From: Fujii Masao <masao.fujii@gmail.com>
To: Marco Nenciarini <marco.nenciarini@enterprisedb.com>
Cc: pgsql-hackers@postgresql.org
Date: 2026-01-29T11:33:11Z
Lists: pgsql-hackers 
On Thu, Jan 29, 2026 at 2:03 AM Marco Nenciarini
<marco.nenciarini@enterprisedb.com> wrote:
>
> Hi hackers,
>
> I've encountered a bug in PostgreSQL's streaming replication where cascading
> standbys fail to reconnect after falling back to archive recovery. The issue
> occurs when the upstream standby uses archive-only recovery.
>
> The standby requests streaming from the wrong WAL position (next segment boundary
> instead of the current position), causing connection failures with this error:
>
>     ERROR: requested starting point 0/A000000 is ahead of the WAL flush
>     position of this server 0/9000000

Thanks for the report!
I was also able to reproduce this issue on the master branch.

Interestingly, I couldn't reproduce it on v11 using the same test case.
This makes me wonder whether the issue was introduced in v12 or later.

Do you see the same behavior in your environment?

Regards,

-- 
Fujii Masao

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix scenario where streaming standby gets stuck at a continuation record.

  2. Allow a streaming replication standby to follow a timeline switch.