On Aug 9, 2011, at 4:37 AM, Stuart Bishop wrote:

> I need to replicate some new databases.
> 
> We have 5 shards, each with an identical schema. Each of these will be
> replicated to a slave (5 masters, 5 slaves).
> 
> Do I need 5 separate clusters, or can I do this with a single cluster
> and 5 replication sets? I'll be using PG 8.4 and Slony-I 2.0.7.
> 
> I suspect I need 5 separate clusters, and I'm less likely to blow my
> foot off with this setup, but I'm soliciting opinions before I proceed
> :-)

Unfortunately the terminology gets overloaded. Do you mean you have 5 different PG clusters, and want a slave for each? Or do you have 1 PG cluster with 5 different schemas in it (which happen to be identical) and want a slave for each schema?

If you have multiple PG clusters, you need multiple slony clusters. If not, then you don't. A replication set can span schemas if you wish it to, and you can also have multiple replication sets per schema.