Re: make pg_ctl more friendly

Hi,

On 2023-11-02 14:50:14 +0800, Crisp Lee wrote:
> I got a basebackup using pg_basebackup -R. After that, I created a restore
> point named test on primary, and set recovery_target_name to test,
> recovery_target_action to shutdown in standby datadir. I got a failure
> startup message  after 'pg_ctl start -D $standby_datadir'. I think it is
> not a failure, and makes users nervous, especially for newbies.
>
> My thought is to generate a recovery.done file if the postmaster receives
> exit code 3 from the startup process. When postmaster  exits, pg_ctl will
> give a more friendly message to users.

I think we can detect this without any additional state - pg_ctl already
accesses pg_control (via get_control_dbstate()). We should be able to detect
your case by issuing a different warning if

a) get_control_dbstate() at the start was *not* DB_SHUTDOWNED
b) get_control_dbstate() at the end is DB_SHUTDOWNED

Greetings,

Andres Freund