Re: pg_ctl failover Re: Latches, signals, and waiting

On Mon, Jan 31, 2011 at 12:35 PM, Tatsuo Ishii <ishii@postgresql.org> wrote:
>> If the "pg_ctl promote" patch will have been committed, I recommend that
>> the C function should send the signal to the startup process rather than
>> creating the trigger file. Because the trigger file is checked every for 5s,
>> which would lengthen the failover time by an average 2.5s.
>
> Ok, probably I could make the function smart enough to signal or not
> by looking at the PostgreSQL version.
>
> BTW is it possible to export following variable in xlog.c?
>
> static char *TriggerFile = NULL;
>
> That would make coding of the C function lot easier.

If you change the function so that it sends the signal or call
system("pg_ctl promote"), exporting that variable seems to
be unnecessary. Because pg_ctl promote can promote
the server even if trigger_file is not supplied. You don't need
to check whether trigger_file is set or not, in the C function.

Regards,

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