Re: Synchronous replication: Promotion of Standby to Primary

Hi,

On Thu, May 14, 2009 at 8:16 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> Hi,
>
> On Mon, May 4, 2009 at 11:07 PM, K, Niranjan (NSN - IN/Bangalore)
> <niranjan(dot)k(at)nsn(dot)com> wrote:
>> Hi,
>>
>> Re-opening the discussion related to triggers to promote standby server.
>> In the earlier dicussion, there were 2 proposals, Trigger based on file
>> and trigger based on signals. I think there was no conclusion on this.
>> http://archives.postgresql.org/pgsql-hackers/2008-12/msg01231.php
>>
>> According to the proposal, it seems to be better if signals are used as
>> we can avoid checking the file existance in the loop. Or the other
>> approach is to use inotify (http://en.wikipedia.org/wiki/Inotify). But
>> portability to other unix like OS is an issue to look for.
>>
>> Could you please get back which is being implemented/ considered for
>> promotion of standby?
>
> I had to choose the trigger file approach last time since the patch
> was also using warm-standby in part. But, in 8.5, synch-rep is
> going to work without warm-standby. So, we can choose also the
> trigger based on signals. In this case,

In this case, I'm not sure which signal can be used for the trigger.
SIGINT/QUIT/TERM/USR1 are already used in postmaster.
SIGUSR2 is already reserved for children according to the source
comment.

Regards,

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