Re: sequencesync worker race with REFRESH SEQUENCES

On Fri, 10 Jul 2026 at 10:22, Noah Misch <noah(at)leadboat(dot)com> wrote:
>
> A Fable 5 review of logical replication of sequences found a way to get
> subscribed sequences into READY state despite the subscriber side having data
> older than the last REFRESH SEQUENCES. I'm attaching the test case it wrote.
> I reviewed the test, and I think it identifies a genuine defect.
>
> Fable 5 also wrote a lot more that neither it nor I confirmed by test case
> construction. I'm attaching the report; feel free to disregard. Finding-2
> about default_transaction_read_only=on looks worth fixing if true, as do
> finding-7 assert failure

I agree that the assertion failure reported in Finding 7 can occur
when a sequence is dropped concurrently while ALTER SUBSCRIPTION ...
REFRESH SEQUENCES is running. I've analyzed the issue and posted a
proposed fix at [1], the thread where the relevant code was originally
introduced.

[1] - https://www.postgresql.org/message-id/CALDaNm2fHGLeiQKj0r6OG7N9QeayxSmpLrWYJRyt4dL_m3VRWw%40mail.gmail.com

Regards,
Vignesh