Re: Issues with Quorum Commit

On Sat, Oct 9, 2010 at 4:31 AM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>> Yes. But if there is no unsent WAL when the master goes down,
>> we can start new standby without new backup by copying the
>> timeline history file from new master to new standby and
>> setting recovery_target_timeline to 'latest'.
>
> .. and restart the standby.

Yes.

> It's a pretty severe shortcoming at the moment. For starters, it means that
> you need a shared archive, even if you set wal_keep_segments to a high
> number. Secondly, it's a lot of scripting to get it working, I don't like
> the thought of testing failovers in synchronous replication if I have to do
> all that. Frankly, this seems more important to me than synchronous
> replication.

There seems to be difference in outlook between us. I prefer sync rep.
But I'm OK to address that first if it's not hard.

> It shouldn't be too hard to fix. Walsender needs to be able to read WAL from
> preceding timelines, like recovery does, and walreceiver needs to write the
> incoming WAL to the right file.

And walsender seems to need to transfer the current timeline history to
the standby. Otherwise, the standby cannot recover the WAL file with new
timeline. And the standby might need to create the timeline history file
in order to recover the WAL file with new timeline even after it's restarted.

Regards,

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