Re: Some questions about mammoth replication

On Thu, 11 Oct 2007 19:10:18 +0300
Alexey Klyukin <alexk(at)commandprompt(dot)com> wrote:

> Marko Kreen wrote:
> > On 10/11/07, Alexey Klyukin <alexk(at)commandprompt(dot)com> wrote:
> > > Hannu Krosing wrote:
> > > > For what use cases do you think your WAL-based approach is
> > > > better than Slony/Skytools trigger-based one ?
> > >
> > > A pure trigger based approach can only replicate data for the
> > > commands which fire triggers. AFAIK Slony is unable to replicate
> > > TRUNCATE command (I don't know if Skytools can). Replicator
> > > doesn't have this limitation.
> >
> > No, Skytools is same as Slony.
> >
> > Can you also replicate changes to system tables?

>
> No, we need a table to have primary key to be able to replicate it.
> From the other hand replicating a system relation can be dangerous,
> i.e. what if you replicate the contents of pg_class without
> corresponing relations on the slave, that's why explicitly forbid
> enabling replication for relations from pg_catalog namespace.

We can however replicate large objects and specific system commands
like GRANT/REVOKE and CREATE/DROP user. The latter being done via
triggers.

Joshua D. Drake

>
> Regards,

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