Bucardo is one of the replication system for PostgreSQL where it works asynchronous and using triggers to replicate the data. And one of the cool feature is you can have multi masters as well as slaves. Since the replication is working on table level to replicate the data, we can use it to replicate partial data and of course DLL is not supported. There are many more features you can look here.
Recently, I have to setup replication from Amazon RDS on one of our busiest databases to another cloud services provider for some reasons. And the only way to do this is using Bucardo.