Re: Sync Rep: First Thoughts on Code

Hi,

On Wed, Dec 24, 2008 at 12:38 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> Perhaps, but why do you say that?

Since you often pointed out that getting backup is not problem because
of incremental backup (e.g. rsync), I just thought so.

> I've not blocked you from adding
> anything useful to Postgres.

Yes, I see.

> You scare me that you see failover as sufficiently frequent that you are
> worried that being without one of the servers for an extra 60 seconds
> during a failover is a problem. And then say you're not going to add the
> feature after all. I really don't understand. If its important, add the
> feature, the whole feature that is. If not, don't.

Oh, sorry. I don't want to scare you ;) But, yes, it's important. We should
rethink the question? "Why does the failed server always need a fresh
backup?" Though we discussed it previously and concluded that it should
be done next time.
http://archives.postgresql.org/pgsql-hackers/2008-11/msg01612.php

> My expectation is that most failovers are serious ones, that the primary
> system is down and not coming back very fast. Your worries seem to come
> from a scenario where the primary system is still up but Postgres
> bounces/crashes, we can diagnose the cause of the crash, decide the
> crashed server is safe and then wish to recommence operations on it
> again as quickly as possible, where seconds count it doing so.
>
> Are failovers going to be common? Why?

As you say, *all* failovers are not serious ones. I think that a user
would choose most convenient restarting method according to his
or her situation (come back immediately? need careful diagnosis?).

Regards,

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