RE: BUG: Former primary node might stuck when started as a standby

Dear Michael,

> Requiring injection points to be enabled so as we have a strict
> control over the standby snapshot records does not strike me as a bad
> requirement in itself. Most of the animals use the switch these days.
> It's a bit sad if this is not entirely stable in pre-v16 branches, but
> a stable post-v17 behavior would always be better than an unstable
> behavior everywhere.

OK, thanks for the clarification. I will create patches for back branches
after it is stabilized on HEAD.
(Current one might be able to be applied, not sure)

> + autovacuum = off
> + checkpoint_timeout = 1h
>
> Why do we need these? An explanation seems in order in the shape of a
> commit, or these should be removed.

I think it is needed to stabilize the test. If checkpointer and/or may generate
the WAL between the switchover, the test can fail with the same reason as bgwriter's
activity. I added comments for it.

> Is there a different trick than the one posted at [1] to check the
> stability of the proposal? I am wondering if I am missing something,
> or if that's all. Alexander?
>
> [1]:
> https://www.postgresql.org/message-id/e1cf52d2-c344-4dfd-a918-e5f20ff04fa
> 2(at)gmail(dot)com

To clarify, I have no knowledge for it.

Best regards,
Hayato Kuroda
FUJITSU LIMITED