From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
---|---|
To: | Dmitry Panov <dmitry(at)tsu(dot)tula(dot)ru> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-general(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: WAL logs multiplexing? |
Date: | 2005-12-29 11:58:06 |
Message-ID: | 1135857486.2964.745.camel@localhost.localdomain |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general pgsql-hackers |
On Thu, 2005-12-29 at 10:47 +0300, Dmitry Panov wrote:
> On Wed, 2005-12-28 at 11:05 -0500, Tom Lane wrote:
> > Dmitry Panov <dmitry(at)tsu(dot)tula(dot)ru> writes:
> > > Yes, but if the server has crashed earlier the script won't be called
> > > and if the filesystem can't be recovered the changes will be lost. My
> > > point is the server should write into both (or more) files at the same
> > > time.
> >
> > As for that, I agree with the other person: a RAID array does that just
> > fine, and with much higher performance than we could muster.
> >
>
> BTW, I found something related in the TODO:
> http://momjian.postgresql.org/cgi-bin/pgtodo?pitr
>
> I think both approaches have the right to exist, but I prefer my because
> it looks more straightforward, it insures up-to-date recovery (no
> delays) and it reduces the traffic (as the partial logs have to be
> transferred in full by the proposed "archive_current_wal_command"). The
> only drawback is performance.
Simply replicating pg_xlog might be worthwhile for the truly paranoid,
since it does help in the situation that you lose the RAID unit with
your pg_xlog on it. But this facility is already available via hardware
replication facilities, so I see no reason to build it into the DBMS.
Replicating pg_xlog to NFS would not work very well performance wise and
has some major undefined behaviour in most failure modes, so I would
never do that.
However, there is a case to be made for "continuous xlog record
archival" which could get closer to 0% data loss in the event of
failure, though with higher performance hit than current PITR. I'll look
into that some more - but no promises.
Best Regards, Simon Riggs
From | Date | Subject | |
---|---|---|---|
Next Message | John Dean | 2005-12-29 13:08:37 | Re: Is CREATE TYPE an alias for CREATE DOMAIN? |
Previous Message | Florian G. Pflug | 2005-12-29 10:48:49 | Re: Adding columns to a view |
From | Date | Subject | |
---|---|---|---|
Next Message | Simon Riggs | 2005-12-29 13:19:45 | Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and |
Previous Message | Simon Riggs | 2005-12-29 10:59:56 | Re: Missing DATE selectivity |