Re: To Signal The postmaster

On Wed, Dec 8, 2010 at 6:22 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Wed, Dec 8, 2010 at 4:59 PM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>> For 9.1, we should think of a better way to do this, perhaps using SIGUSR1
>> to wake up. Maybe we won't even need the trigger file anymore.
>
> If we use SIGUSR1, the mechanism to allow the users to specify the event type
> seems to be required. For example, we should make the SIGUSR1 handler
> check not only the shmem (i.e., PMSignalStat) but also the file?

What I'm thinking is to make something like "pg_ctl promote" create the event
file specifying the standby promotion in $PGDATA/pg_event or elsewhere,
and send SIGUSR1 to postmaster. OTOH, when SIGUSR1 arrives, postmaster
checks whether that event file exists. If it does, postmaster removes it and
sends the signal to startup process for standby promotion.

Thought?

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center