>> Yeah. I think we need some from help backend for this. For example, a
>> parameter status message can be used here. If PostgreSQL moves to the
>> recovery state or vice versa, PostgreSQL sends the parameter status
>> message to frontend.
>>
>
> If we would use parameter status messages, then can we handle compatibility
> correctly? So that new psql can work with old backend without errors (and
> without recovery status display, for sure),
I suppose so.
> and old psql can work with new
> backend without errors.
It should work because any frontend program should ignore parameter
status messages they do not know, according to the docs.
> Because seeing recovery status in psql prompt is very neat. But execution
> of extra query each time doesn't seem like reasonable price for it...
I think so.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
