Re: Add a hint when postgresql.conf hot_standby = 'off' and recovery.conf standby = 'on'

On Fri, May 22, 2015 at 4:22 PM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> On 05/22/2015 06:53 AM, Matthew Kelly wrote:
>>
>> Why anybody in practice would want hot_standby off while in standby
>> mode eludes me, but these are our default values (recovery.conf was
>> generated by pg_basebackup -R).
>
>
> That's how you set up a cold standby system.
>
>> It seems worth adding a hint and/or changing the error message to be
>> more descriptive when in this state.  Any options about what should
>> be logged before I start putting together a patch?
>
>
> Yeah, might be worthwhile. Perhaps:
>
> FATAL:  the database system is in standby mode and hot_standby is not
> enabled

Since we may connect to the server even during an archive recovery (e.g.,
recovery_target_action = pause case), this message should be changed
as follows?

FATAL:  the database system is in standby or archive recovery mode and
hot_standby is not enabled

>
> Or just:
>
> FATAL:  the database system is in cold standby mode
>
> It would be useful to distinguish that state, where you could connect if hot
> standby was enabled, from the state where it's starting up and hasn't
> reached min-recovery-point yet and you couldn't connect even if hot_standby
> was enabled. Not sure how much signalling you'd need between postmaster and
> the startup process for that.

Probably we need to make the startup process send the SIGUSR1 signal to
postmaster when it reaches the consistent point even if hot_standby is not
enabled.

Regards,

-- 
Fujii Masao