Re: Configuring synchronous replication

On Fri, 2010-09-17 at 21:20 +0900, Fujii Masao wrote:
> On Fri, Sep 17, 2010 at 8:31 PM, Simon Riggs  wrote:
> > The only thing standby registration allows you to do is know whether
> > there was supposed to be a standby there, but yet it isn't there now. I
> > don't see that point as being important because it seems strange to me
> > to want to wait for a standby that ought to be there, but isn't anymore.
> 
> According to what I heard, some people want to guarantee that all the
> transactions are *always* written in *all* the synchronous standbys.
> IOW, they want to keep the transaction waiting until it has been written
> in all the synchronous standbys. Standby registration is required to
> support such a use case. Without the registration, the master cannot
> determine whether the transaction has been written in all the synchronous
> standbys.

You don't need standby registration at all. You can do that with a
single parameter, already proposed:

quorum_commit = N.

But most people said they didn't want it. If they do we can put it back
later.

I don't think we're getting anywhere here. I just don't see any *need*
to have it. Some people might *want* to set things up that way, and if
that's true, that's enough for me to agree with them. The trouble is, I
know some people have said they *want* to set it in the standby and we
definitely *need* to set it somewhere. After this discussion, I think
"both" is easily done and quite cool.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Development, 24x7 Support, Training and Services