In response to Martín Marqués <martin.marques at gmail.com>:

> I'm about to start a project that will need to have 2 servers synced.
> 
> The problem is that one server receives modification for some tables
> (that don't get modified on the other server), and the other server
> gets modification for other tables.
> 
> Is it possible to have two slon processes synchronizing changes from
> one server to the other?

Yes.  Replication sets define tables and where they get replicated to
and from.  It's incredibly flexible, and I don't see any issues with
what you're proposing.

> The other thing is that the servers will be in buildings far away, but
> on a 1Gig FO network. Downtime could appear if there is a FO cut,
> which could take some hours to bring up.

Slony was designed specifically to handle this situation.  In my personal
experience with it, it handles it quite well.

It's not designed to handle frequent outages (like a laptop that is
frequently turned off altogether will probably not work).  But for the
occasional incident where the ISP screws up something and is down for
several hours, Slony's recovery ability is quite impressive.

-- 
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/