Re: Proposal for a cascaded master-slave replication system

Jan Wieck wrote:
> http://developer.postgresql.org/~wieck/slony1.html

Very interesting read. Nice work!

> We want to build this system as a community project. The plan was from
> the beginning to release the product under the BSD license. And we think
> it is best to start it as such and to ask for suggestions during the
> design phase already.

I couldn't quite tell from the design doc -- do you intend to support 
conditional replication at a row level?

I'm also curious, with cascaded replication, how do you handle the case 
where a second level slave has a transaction failure for some reason, i.e.:

             M
            / \
           /   \
         Sa     Sb
        /  \   /  \
       Sc  Sd Se  Sf

What happens if data is successfully replicated to Sa, Sb, Sc, and Sd, 
and then an exception/rollback occurs on Se?

Joe