On Tue, 2009-04-28 at 18:44 +0200, marco perugini wrote:
> hi brad! first of all thanks for your feedback.
> now i want to be sure i well understand your answer:
> i'm replicating db1 from cluster A [provider] to cluster B
> [subscriber]; now i want to replicate another db
> [ie db2] from cluster B [which should become a provider too] to
> another db server [called C in my first mail].
> in this scenario i don't have multiple provider but a sort of
> replication's chain for 2 different dbs: db1 from
> A to B and db2 from B to C. so can B's slon process be provider and
> subscriber at the same time?
> however i'm using slony 2.0.0.
> thanks in advance!
> marco

You can run this configuration - it is supported by Slony.

However, since they are in separate databases, you will need to run
different instances of the slons to replicate.

> 
> Brad Nicholson ha scritto: 
> > On Tue, 2009-04-28 at 14:53 +0200, marco perugini wrote:
> >   
> > > Dear all I have a little question, about a real scenario.
> > > I have this in my network:
> > >   - A database cluster, call A, where live master instance of Slony;
> > >   - A database cluster, call B, where live slave instance of Slony;
> > >   - A simple database, call C, where i'd like to have a replication.
> > >   
> > > So, at now A is master and replicate a schema (call S1) over the database B, the slave. 
> > > I need to create another schema (call S2) in B that must replicate over the simple database C(S2 schema slave).
> > > My question is:  can I have a Master process of Slony (for instance in B) where is live a slave process?
> > > If yes, how can i configure it. If No, how can I do with this environment?
> > > Thanks everybody for help.
> > > Regards,
> > > marco
> > >     
> > 
> > Yes, you can do this.  You would use one set for S1, making the node on
> > cluster A the provider, and Cluster C a replica.  You would create
> > another set for S2, making the node on Cluster B the provider and
> > cluster C the replica.  The same set of slons will service this cluster.
> > 
> > A couple words of warning with this configuration though 
> > 
> > -I'm not sure if you want to have Cluster B also be a replica of of the
> > set  S1.  If this the case, you will not be able to rely on pg_dump for
> > dumping cluster B if you are using a version of Slony prior to 2.0.x.
> > This will be a mixed cluster (a provider and a replica), the catalogs
> > are corrupted (by design) on a replica.
> > 
> > -We have found the multiple provider clusters to be highly error prone.
> > There is no problem when replicating data (we've never had a problem
> > with regular operation), but config changes often don't behave as
> > intended, and often result in lost nodes.
> > 
> >   
> 
> -- 
> 4it
> 
> 
> 4IT S.r.l.
> Marco Perugini | system
> administrator 
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-- 
Brad Nicholson  416-673-4106
Database Administrator, Afilias Canada Corp.