Re: Slony for upgrades

Robert Treat wrote:
> On Tuesday 16 October 2007 01:38, Bruce Momjian wrote:
> > Jeff Frost wrote:
> > > On Mon, 15 Oct 2007, Bruce Momjian wrote:
> > > > Seems we didn't have any mention of Slony for upgrades in the migration
> > > > section, so I added it:
> > > >
> > > >  <para>
> > > >   It is also possible to use <productname>Slony</> to create a slave
> > > >   server with the updated version of <productname>PostgreSQL</>.  The
> > > >   slave can be on the same computer or a different computer.  Once it
> > > >   has synced up with the master server (running the older version of
> > > >   <productname>PostgreSQL</>), you can switch masters and make the
> > > > slave the master and shut down the older database instance.  Such a
> > > > switch-over results in only several minutes of downtime for an upgrade.
> > > > </para>
> > >
> > > Bruce, do you think we should say several minutes of downtime?  It's been
> > > my experience that the downtime is usually measurable in seconds.  I
> > > don't think I've ever had a switchover take more than 1 minute.
> > >
> > > Excellent catch and good work by the way!
> >
> > Thanks, changed to seconds.  I thought someone told me <5 minutes a
> > while ago but I might have been mistaken.
>
> I might question the strict reference to Slony here. AIUI you could do the
> same thing with Bucardo and a couple of other replication solutions as well.

OK, I now say "like Slony":

   It is also possible to use replication like <productname>Slony</> to
   create a slave server with the updated version of
   <productname>PostgreSQL</>.  The slave can be on the same computer or
   a different computer.  Once it has synced up with the master server
   (running the older version of <productname>PostgreSQL</>), you can
   switch masters and make the slave the master and shut down the older
   database instance.  Such a switch-over results in only several seconds
   of downtime for an upgrade.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://postgres.enterprisedb.com

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