Re: Synchronous replication: Promotion of Standby to Primary

Hi,

On Mon, May 25, 2009 at 7:10 PM, Kolb, Harald (NSN - DE/Munich)
<harald(dot)kolb(at)nsn(dot)com> wrote:
> Hello Fujii,
>
> my name is Harald Kolb, I'm a colleague of Niranjan and I will continue
> his community work since he's currently busy with other topics.
> We are looking for a fast mechanism to activate the switchover. Therfore
> we prefer to use a signal to trigger the standby to become primary,
> since in our case the postmaster will be started via fork by a watchdog.
> The originally intended solution via SIGTERM should be ok.
> In the case the mechanism will be still based on the trigger file
> concept, we would require to have in addition a signal to speed up the
> trigger file detection, since the periodic check might be not fast
> enough.

To be honest, I don't think that such quick detection shortens
the failover time so much (probably it would be shortened only
a few ms). Instead, we should reduce the time of checkpoint
which occurs at the end of recovery/failover. It might take a few
minutes to end. So, I'd like to emphasize user-friendliness
rather than the failover time in the choice of the way of activation.
What is your opinion?

Regards,

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