Re: dbmirror

The sequences do not update automatically on the slave(s) in the version we are running ... we do have a cron job that
kicksoff every few minutes and updates them based opn the current value of their respective columns, which so far has
beenall we needed. 
G

-----Original Message-----
From:    Fred Fung [mailto:fred.fung@versaterm.com]
Sent:    Fri 5/14/2004 6:11 AM
To:    pgsql-general@postgresql.org
Cc:
Subject:    Re: [GENERAL] dbmirror
Thanks for all your comments.

Is it really true that the sequences in the tables in the Slaves will not be
in sync with those in the Master ? If so then this is a show-stopper factor
for us to consider using dbmirror, as we use sequences as a unique key in
many of the tables in our application.

What is Slony-I ? Is it a commerical software ? Is there a website I can
read more about it ?


Thanks.


Fred


----- Original Message -----
From: "Gregory Wood" <gwood@ewebengine.com>
To: "Andrew Sullivan" <ajs@crankycanuck.ca>
Cc: <pgsql-general@postgresql.org>
Sent: Thursday, May 13, 2004 4:10 PM
Subject: Re: [GENERAL] dbmirror


> Does dbmirror do that? No, it does not. It also doesn't support
> promoting a slave database to a master; that has to be done manually, so
> I wouldn't consider that too big a problem.
>
> Worse in my opinion is that sequences don't get updated... so a slave
> that tries to do an insert on a replicated table (for example, when it
> gets manually promoted to master) will find the sequence not where the
> master left it, but where it was loaded. Every sequence has to be
> manually updated before the database is usable.
>
> dbmirror was never intended to be anything but a poor man's
> replication... and it worked remarkably well for that purpose. Now it's
> time to look forward to Slony-I :)
>
> Greg
>
> Andrew Sullivan wrote:
> > On Wed, May 12, 2004 at 05:53:05PM -0700, Gregory S. Williamson wrote:
> >
> >>Fred --
> >>
> >>Yes, the slave database(s) can be safely used in a R/O mode,
> >
> >
> > Does it also block write transactions in those slaves?  The ability
> > for clients to write into the slave replicated tables is a problem,
> > because it makes promoting a slave node somewhat risky.
> >
> > Slony-I has a trick to solve this problem, BTW.
> >
> > A
> >
>
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