Slony

One of the oldest and most mature PostgreSQL replication solutions, Slony is both a complex and feature rich replication program; refer to http://slony.info/.

It's written in C and highly optimized for the form of replication it does. Much of the development work on Slony is done by Afilias, who use Slony for both redundancy and load scaling for a significant portion of the Internet Domain Name Service. It aims at that reliability level.

Slony is a complicated program, which is reflected everywhere from initial setup complexity to extensive monitoring requirements. Expect to devote a significant amount of study to any Slony deployment. The return on that time investment is quite a powerful replication solution with many years worth of thought put into its feature set.

One of the limitations of Slony to be aware of is that every table it replicates needs to have a primary or similar key field for it to operate over.