> I agree with you.  But do we actually need a
> wait_for_standby_and_slot_catchup() wrapper.  I think we can call
> $node->wait_for_slot_catchup() directly and simplify the fix.  Check
> the attached patch.
>

The patch looks good to me. I agree that the wait_for_slot_catchup is
not needed and could be misleading. This change would make the exact
synchronization point and its intention clearer. The only price we
need to pay here is bringing back the polling. But it seems acceptable
since the cost was there in the pre-wait-for-lsn era. And thanks for
writing the great commit message!