pgq is the backbone of a replication tool called
londiste. The idea of
londiste is to have a mechanism that is more simplistic and easier to use than, say, Slony. If you use Slony in a large installation, it is very easy for a problem on one side of the cluster to cause some issues at some other point—this was especially true many years ago when Slony was still fairly new.
The main advantage of
londiste over Slony is that in the case of
londiste replication there will be one process per "route". So, if you replicate from A to B this channel will be managed by one
londiste process. If you replicate from B to A or from A to C those will be separate processes, which are totally independent from each other. All channels ...