From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
---|---|
To: | "Kolb, Harald (NSN - DE/Munich)" <harald(dot)kolb(at)nsn(dot)com> |
Cc: | "K, Niranjan (NSN - IN/Bangalore)" <niranjan(dot)k(at)nsn(dot)com>, "Czichy, Thoralf (NSN - FI/Helsinki)" <thoralf(dot)czichy(at)nsn(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Synchronous replication: Promotion of Standby to Primary |
Date: | 2009-05-25 12:10:25 |
Message-ID: | 3f0b79eb0905250510s75f8ebccn4155a916f39f6cd5@mail.gmail.com |
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Lists: | pgsql-hackers |
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
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