Re: Configuring synchronous replication

On Fri, Sep 17, 2010 at 8:43 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Fri, Sep 17, 2010 at 5:09 PM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>> * Quorum commit. Wait until n standbys acknowledge. n=1 and n=all servers
>> can be seen as important special cases of this.
>
> I think that we should skip quorum commit at the first phase
> because the design seems to be still poorly-thought-out.
>
> I'm concerned about the case where the faster synchronous standby
> goes down and the lagged synchronous one remains when n=1. In this
> case, some transactions marked as committed in a client might not
> be replicated to the remaining synchronous standby yet. What if
> the master goes down at this point? How can we determine whether
> promoting the remaining standby to the master causes data loss?

Yep. That issue has been raised before, and I think it's quite valid.
That's not to say the feature isn't valid, but I think trying to
include it in the first commit is going to lead to endless wrangling
about design.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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