Re: BUG #19490: Streaming standby on 16.14 stops applying WAL on MultiXactOffsetSLRU when primary is 16.8

Thanks for the report!

Oh, this seems to be from the "gift that keeps on giving" department.
Related to [0]

> On 20 May 2026, at 14:16, PG Bug reporting form <noreply(at)postgresql(dot)org> wrote:
>
> Downgrading the standby binary to 16.12 (16.12-1.pgdg22.04+1) against
> the same data directory restored normal replay. After 60s under the same
> workload pg_stat_slru shows only 2 hits / 0 reads on MultiXact.

Are you sure that it's not 16.11 that is resolving the problem?
Can you get a backtrace of hanging startup process with debug symbols? Or obtain last
replayed LSN and do a WAL dump in the area of deadlocked startup.

I don't see how this might be a result of [1] and [2], so, perhaps, it's some more peculiarities
from [3]. But 16.12 has [3]...

Best regards, Andrey Borodin.

[0] https://www.postgresql.org/message-id/flat/CACV2tSw3VYS7d27ftO_cs%2BaF3M54%2BJwWBbqSGLcKoG9cvyb6EA%40mail.gmail.com
[1] https://git.postgresql.org/cgit/postgresql.git/commit/?h=REL_16_STABLE&id=77dff5d937b192b85c55bce822e7413ff7dda6eb
[2] https://git.postgresql.org/cgit/postgresql.git/commit/?h=REL_16_STABLE&id=23064542f8bdcbc4b6a513cac8ceed67c0d2336e
[3] https://git.postgresql.org/cgit/postgresql.git/commit/?h=REL_16_STABLE&id=6351669130782ed01eed3aeefded171789d0bc35